Monad newbie question
Hello, I've never used monads but I have a problem that feels like it could be solved elegantly with them. I have a sequence of functions of arbitary size and an input sequence s. Each function is given a sequence and returns a sequence that can be bigger than the input sequence. I want the output of one function to be operated on using a mapcat of the next function: (let [seq-of-fns [f1 f2 f3 ... fm]] (mapcat fm ... (mapcat f2 (mapcat f1 s))) If any of the functions return nil, I'd like the computation to stop. This seems like something that should be possible with the maybe-m in clojure.contrib.monad but I don't understand how to do the following: 1. How do I handle an arbitary seq-of-fns [f1 f2 ... fm]? 2. How can I specify that I want a function to mapcat the return value of the previous function? I've read the monad tutorials linked at http://richhickey.github.com/clojure-contrib/monads-api.html which have been very useful but any extra help would be appreciated. Thanks in advance Saul -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Monad newbie question
On Jan 13, 9:18 am, Saul Hazledine shaz...@gmail.com wrote: Hello, I've never used monads but I have a problem that feels like it could be solved elegantly with them. I have a sequence of functions of arbitary size and an input sequence s. Each function is given a sequence and returns a sequence that can be bigger than the input sequence. I want the output of one function to be operated on using a mapcat of the next function: Sorry, I explained that wrong. Each function takes a single item and returns a sequence - this is why mapcat is used. Saul -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: When to use #'
One common case also, is if you want to store in a datastructure not the
current function of a global var, but rather the var itself, so that
everytime you want to use it, you'll get the current value bound to the var,
and not the value bound that happened to be bound to the var when at the
point in time it was stored in the datastructure.
By example:
(defn toupper [s] (.toLowerCase s))
#'user/toupper
(def str-funs {:to-upper toupper})
#'user/str-funs
((:to-upper str-funs) Foo)
foo
; arg, let's change toupper definition (e.g. the root value associated to
the toupper var)
(defn toupper [s] (.toUpperCase s))
#'user/toupper
; now let's call the to-upper function ...
((:to-upper str-funs) Foo)
foo
; arg, still the old definition. Oh wait ! In the str-fun defs, toupper has
been evaluated to its root value, and I've stored a function in the
datastructure
; let's store the toupper var itself
; let's retry all this again, to be sure
(defn toupper [s] (.toLowerCase s))
#'user/toupper
(def str-funs {:to-upper #'toupper}) ; or (var toupper), if you don't like
the #' reader macro
#'user/str-funs
((:to-upper str-funs) Foo)
foo
; ok so now let's redefine toupper
(defn toupper [s] (.toUpperCase s))
#'user/toupper
((:to-upper str-funs) Foo)
FOO
; Yay !
2011/1/13 rob levy r.p.l...@gmail.com
One common use is for referring to private functions in other namespaces.
For example, say you want to write tests for foo.core/p, a privately
defined function. It is private in terms of your intent as expressed in
your API, but you can still access the var from foo.core-test and call the
function in your tests as #'foo.core/p.
On Wed, Jan 12, 2011 at 10:29 PM, gaz jones gareth.e.jo...@gmail.comwrote:
its a reader macro equivalent to the var special form:
(var symbol)
The symbol must resolve to a var, and the Var object itself (not its
value) is returned. The reader macro #'x expands to (var x).
from:
http://clojure.org/special_forms#var
On Wed, Jan 12, 2011 at 9:11 PM, Alex Baranosky
alexander.barano...@gmail.com wrote:
Hi, I find it extremely hard to google this to learn more! I'd like to
know some good sources of further information on when to use #' . It is
a
bit mysterious to me at this point.
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Re: Compiling dynamically created namespaces, without on-disk source code?
On a related note, is there any way to completely clear all the bytecode that's being stored internally by the jvm, forcing it to fall back to the hard-disk version of the classfiles available on the classpath? sincerely, --Robert McIntyre On Tue, Jan 11, 2011 at 5:04 PM, Stuart Sierra the.stuart.sie...@gmail.com wrote: You would have to capture the source form of each definition before it's compiled. Not too hard if you hack the REPL a bit; someone has probably already worked on it. -S -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: How do I find implemented protocols in Clojure object?
I tried to do it the other way around: find all symbols in a given namespace and use your protocol? function to find out which of these is a protocol, and next check with extenders if the class of my object is included. However this fails because my code to get all symbols from a namespace: (map #(% 0) (ns-publics *ns*)) exactly does that: it gives the symbol names. The protocol? function doesn't work for a symbol, but needs the actual protocol as parameter. To make myself hopefully a little bit more clear: (defprotocol P (bar [x])) (println (isprotocol? P)) prints true (map #(isprotocol? (% 0)) (ns-publics *ns*))) just returns sequence which only contains false values. Maurits On Jan 12, 10:48 pm, Bob Hutchison hutch-li...@recursive.ca wrote: On 2011-01-12, at 8:38 AM, Stuart Sierra wrote: One way: (ancestors (type the-object)) This will include every interface implemented by the object, including protocols. This seems to only work if the protocol is mentioned in the defrecord. If it's applied using the extend function it doesn't seem to show the protocol. The functions bases and supers work similarly. Unless I'm doing something really stupid, which is a distinct possibility. Any idea how to tell which of the classes returned by ancestors/bases/supers are protocols? I copied a function from the source that can tell if something is a protocol if written directly in clojure, but does not work on the results from those methods. (defn protocol? [maybe-p] (boolean (:on-interface maybe-p))) Cheers, Bob -S clojure.com -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en Bob Hutchison Recursive Design Inc.http://www.recursive.ca/ weblog:http://xampl.com/so -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: How do I find implemented protocols in Clojure object?
Hi, Try this: (map #(isprotocol? @(val %)) (ns-publics *ns*))) However just checking extenders is not enough, because it does not contain classes, which implement the protocol directly. Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: [ANN] fs - file system utilities for Clojure
I'm missing something blindingly obvious. Where can I download this? On Wed, Jan 12, 2011 at 3:48 PM, Miki miki.teb...@gmail.com wrote: [fs 0.2.0-SNAPSHOT] is out, featuring: abspath Return absolute path basename Return the last part of path copy Copy a file cwd Return the current working directory delete Delete path directory? True if path is a directory dirname Return directory name executable? Check if path is executable exists? Check if path exists file? True if path is a file glob `ls` like operator join Join part to path listdir List files under directory mkdir Create directory mtime File modification time mkdirs Create directory tree normpath Return normalized (canonical) path readable? Check if path is readable rename Rename path separator Path separator size File size split Split path to parts tempdir Create temporary directory tempfile Create temporary file walk Walk over directory structure, calling function on every step writeable? Check if path is writable Have fun, -- Miki -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: How do I find implemented protocols in Clojure object?
Thanks for your answer. I guess the right approach is to check with extends? against the list of protocols that I found in the namespace. Maurits On Jan 13, 2:00 pm, Meikel Brandmeyer m...@kotka.de wrote: Hi, Try this: (map #(isprotocol? @(val %)) (ns-publics *ns*))) However just checking extenders is not enough, because it does not contain classes, which implement the protocol directly. Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: How do I find implemented protocols in Clojure object?
Hi, On 13 Jan., 14:15, Maurits maurits.r...@gmail.com wrote: Thanks for your answer. I guess the right approach is to check with extends? against the list of protocols that I found in the namespace. Actually satisfies? with an instance of the class in question. Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: fs - file system utilities for Clojure
Hi, On 12 Jan., 21:48, Miki miki.teb...@gmail.com wrote: [fs 0.2.0-SNAPSHOT] is out A SNAPSHOT is out? Please don't do this. If it is a release, get rid of the SNAPSHOT. :( Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: [ANN] fs - file system utilities for Clojure
probably clojars.org (or by putting [fs 0.2.0-SNAPSHOT] in your project.clj if you're using lein... On Thu, Jan 13, 2011 at 7:11 AM, Tim Visher tim.vis...@gmail.com wrote: I'm missing something blindingly obvious. Where can I download this? On Wed, Jan 12, 2011 at 3:48 PM, Miki miki.teb...@gmail.com wrote: [fs 0.2.0-SNAPSHOT] is out, featuring: abspath Return absolute path basename Return the last part of path copy Copy a file cwd Return the current working directory delete Delete path directory? True if path is a directory dirname Return directory name executable? Check if path is executable exists? Check if path exists file? True if path is a file glob `ls` like operator join Join part to path listdir List files under directory mkdir Create directory mtime File modification time mkdirs Create directory tree normpath Return normalized (canonical) path readable? Check if path is readable rename Rename path separator Path separator size File size split Split path to parts tempdir Create temporary directory tempfile Create temporary file walk Walk over directory structure, calling function on every step writeable? Check if path is writable Have fun, -- Miki -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: fs - file system utilities for Clojure
[fs 0.2.0-SNAPSHOT] is out A SNAPSHOT is out? Please don't do this. If it is a release, get rid of the SNAPSHOT. :( Done, please use [fs 0.2.0] :) All the best, -- Miki -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: How do I find implemented protocols in Clojure object?
Thanks for all the feedback and answers. I have added my implementation below. Maurits - ; test protocol and record (defprotocol Log (log [this] Method to log)) (defrecord Foo [f1 f2] Log (log [this] (println (:f1 this) (:f2 this (def foo (Foo. 13 42)) (log foo) ; the relevant stuff (defn protocol? [maybe-p] (boolean (:on-interface maybe-p))) (defn all-protocols [] (filter #(protocol? @(val %)) (ns-publics *ns*))) (defn implemented-protocols [sym] (filter #(satisfies? @(val %) sym) (all-protocols))) (println (implemented-protocols foo)) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: [ANN] fs - file system utilities for Clojure
I'm missing something blindingly obvious. Where can I download this? probably clojars.org (or by putting [fs 0.2.0-SNAPSHOT] in your project.clj if you're using lein... Yup, it's in clojars. However if you prefer to download the jar manually, you can get it from https://bitbucket.org/tebeka/fs/downloads/fs-0.2.0.jar All the best, -- Miki -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: [ANN] fs - file system utilities for Clojure
2011/1/13 Miki miki.teb...@gmail.com I'm missing something blindingly obvious. Where can I download this? probably clojars.org (or by putting [fs 0.2.0-SNAPSHOT] in your project.clj if you're using lein... Yup, it's in clojars. However if you prefer to download the jar manually, you can get it from https://bitbucket.org/tebeka/fs/downloads/fs-0.2.0.jar Too bad the artifact name f was already taken, and you had to resort to using a sooo long name as fs :-p Just kidding ;) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: [ANN] fs - file system utilities for Clojure
Thanks for shaing. I was just about to write several functions along these lines. I have a couple of comments. First, I suggest that you look at the standard clojure.java.io package for some useful functions that are already in Clojure 1.2. In particular, you could use io/file instead of (File. xxx) in your code to add some flexibility to the kinds of things that can be treated as a file. I think io/file could replace your fs/join. Also, io/copy is very flexible so it's worth a look, too. Second, fs is using a singe segment namespace. I remember that there have been some cautions against doing that. (But not everyone agrees.) My understanding is that it's best for Java interop to have a multi-segment namespace. (Reference links below.) http://clojure.org/libs A lib name is a symbol that will typically contain two or more parts separated by periods. http://groups.google.com/group/clojure-dev/browse_frm/thread/00b1c6971c3b3394 Chas Emerick wrote: First, namespacing is good. Your foobar library won't have the same name as my foobar library -- and while you might think who else would put code in the same oddly-named namespace as mine?, it's a big world out there and an ounce of prevention is worth a pound of cure. More strictly speaking, one cannot use any class in the default package from any Java class that is in a package. That is the practical issue that leads to default package use being nonexistent in the Java space. And, you may not care about Java interop now, but either (a) you might later, or (b) your users might, now. Finally, gen-class will simply not work (last I checked) from a single-segment namespace. Best Regards, Steve Miner stevemi...@gmail.com -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Question On Implicit Recursion
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: Question On Implicit Recursion
A literal set is a unordered hash-set. To get the factors in order
change #{f} for (sorted-set f).
On Jan 13, 7:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: [ANN] fs - file system utilities for Clojure
there is also this: https://github.com/jashmenn/clj-file-utils which seems to be very similar On Thu, Jan 13, 2011 at 9:04 AM, Steve Miner stevemi...@gmail.com wrote: Thanks for shaing. I was just about to write several functions along these lines. I have a couple of comments. First, I suggest that you look at the standard clojure.java.io package for some useful functions that are already in Clojure 1.2. In particular, you could use io/file instead of (File. xxx) in your code to add some flexibility to the kinds of things that can be treated as a file. I think io/file could replace your fs/join. Also, io/copy is very flexible so it's worth a look, too. Second, fs is using a singe segment namespace. I remember that there have been some cautions against doing that. (But not everyone agrees.) My understanding is that it's best for Java interop to have a multi-segment namespace. (Reference links below.) http://clojure.org/libs A lib name is a symbol that will typically contain two or more parts separated by periods. http://groups.google.com/group/clojure-dev/browse_frm/thread/00b1c6971c3b3394 Chas Emerick wrote: First, namespacing is good. Your foobar library won't have the same name as my foobar library -- and while you might think who else would put code in the same oddly-named namespace as mine?, it's a big world out there and an ounce of prevention is worth a pound of cure. More strictly speaking, one cannot use any class in the default package from any Java class that is in a package. That is the practical issue that leads to default package use being nonexistent in the Java space. And, you may not care about Java interop now, but either (a) you might later, or (b) your users might, now. Finally, gen-class will simply not work (last I checked) from a single-segment namespace. Best Regards, Steve Miner stevemi...@gmail.com -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Java namespaces, Cobol, and Hierarchical file systems
Second, fs is using a singe segment namespace. I remember that there have been some cautions against doing that. (But not everyone agrees.) My understanding is that it's best for Java interop to have a multi-segment namespace. (Reference links below.) http://clojure.org/libs A lib name is a symbol that will typically contain two or more parts separated by periods. http://groups.google.com/group/clojure-dev/browse_frm/thread/00b1c6971c3b3394 Chas Emerick wrote: First, namespacing is good. Your foobar library won't have the same name as my foobar library -- and while you might think who else would put code in the same oddly-named namespace as mine?, it's a big world out there and an ounce of prevention is worth a pound of cure. More strictly speaking, one cannot use any class in the default package from any Java class that is in a package. That is the practical issue that leads to default package use being nonexistent in the Java space. And, you may not care about Java interop now, but either (a) you might later, or (b) your users might, now. Finally, gen-class will simply not work (last I checked) from a single-segment namespace. As a greybeard in the game, this all sounds so familiar. The point of this post is to suggest that Clojure should NOT adopt java naming conventions. Back in the days of Cobol, before it got renamed to Java, we used to construct hierarchical databases. For those who don't know about them, they would specifiy the path to every element in the database in the name of the element. Thus, you would say world.country.company.site.disk.dbname.dept.bldg.aisle.office.person or some such. It was argued that this was necessary to ensure that you always got a unique element and that programs would not clash. It was also very efficient since the worldwide path to a point was always unique (as opposed to the horribly inefficient idea of using table and relational algebra to look up stuff at runtime! Why the ambiguity will cause world confusion and the runtime will be impossibly long! Just write out the long name! Sigh.) There are a couple of items worth mentioning. First, notice that everything is fine until the world changes. Now there are hardcoded legacy assumptions built into the name (e.g. the person is in a different building so we have to reformat the database to pay them). Consider that the Java naming convention does that... java.sun.com ... who is sun? I never heard of them. Second, but similar, should I name my classes java.daly.tim.freesource? Suppose I get married and change my name? Suppose someone with a similar name writes a package. Does my son have to write java.jr.daly.tim.freesource? Third, suppose I refactor my program. Now I have to rename every class to fit the new hierarchy. But that will break old programs that use my package. Who could possibly want to refactor deep enough to shuffle classes? Fourth, this hierarchical thinking strongly encourages making functions that are class-specific. Thus you find that java has hundreds of sorts, one per class. Fifth, one writes the long.drawn.out.name to satify the compiler's inability to find anything despite the class name being unique. In fact, the compiler is insisting that your class name match the name of the file and it STILL insists that you use unique names so it doesn't have to search the filesystem. The side-effects of this are that your class hierarchy is rigid (see refactoring above), the name assumes a hierarchical file system, and the ultimate issue... the user has to use an IDE to find something simple as a sort. Sixth, programs rarely need to deal with the whole world. Why would you have qualifiers on a per-company basis just to guarantee uniqueness of the name of your sort function? In lisp one ends up with hundreds of functions in the same namespace. Because the functions are not type-specific they tend to be very broad and general. It is rare to have more than one sort and people don't generally write sort functions since they are too standard. A simple namespace qualifier, like fs, is sufficient to handle large, general purpose packages which contain functions to handle file systems. Since lisp uses naked functions there is no natural map from functions to filenames. In sum, I'm suggesting that it isn't very lispy to use hierarchical namespace naming conventions. Tim Daly -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Question On Implicit Recursion
Armando, thanks for a plausible explanation. Here is what happened
after I made the suggested change:
user= (prime-factors 600851475143)
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#CompilerException java.lang.ClassCastException: java.lang.Integer
cannot be cast to clojure.lang.IFn (REPL:91)
I guess this something subtle with unordered vs. sorted-set as
implicit factors accumulator. May be that is why the author of the
solution had to use unordered set followed by (apply max ...).
On Jan 13, 11:23 am, Armando Blancas armando_blan...@yahoo.com
wrote:
A literal set is a unordered hash-set. To get the factors in order
change #{f} for (sorted-set f).
On Jan 13, 7:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: How do I find implemented protocols in Clojure object?
On 13 January 2011 15:52, Maurits maurits.r...@gmail.com wrote: (defn all-protocols [] (filter #(protocol? @(val %)) (ns-publics *ns*))) (defn implemented-protocols [sym] (filter #(satisfies? @(val %) sym) (all-protocols))) Of course, this will restrict your search to protocols in a given namespace. It might make sense to also add defrecords and deftypes to the protocol's :impls map if they explicitly extend the protocol at definition time, or to a new :direct-impls set, and make (extenders P) return a union of these so it could always return all implementors of protocol P. Or would this entail problems I don't see at the moment? Daniel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Question On Implicit Recursion
Armando's suggested change worked fine for me.
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
(sorted-set f)
(conj (prime-factors (/ n f)) f
user= (prime-factors 600851475143)
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 1471 6857}
On Jan 13, 10:01 am, Vitaly Peressada vit...@ufairsoft.com wrote:
Armando, thanks for a plausible explanation. Here is what happened
after I made the suggested change:
user= (prime-factors 600851475143)
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#CompilerException java.lang.ClassCastException: java.lang.Integer
cannot be cast to clojure.lang.IFn (REPL:91)
I guess this something subtle with unordered vs. sorted-set as
implicit factors accumulator. May be that is why the author of the
solution had to use unordered set followed by (apply max ...).
On Jan 13, 11:23 am, Armando Blancas armando_blan...@yahoo.com
wrote:
A literal set is a unordered hash-set. To get the factors in order
change #{f} for (sorted-set f).
On Jan 13, 7:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: Question On Implicit Recursion
Benny, thanks for your explanation. It does make sense and clarifies
the issue. What DOES NOT make sense is
Clojure 1.2.0
user= (conj (conj (conj #{4} 3) 2) 1)
#{1 2 3 4}
user= (conj (conj (conj #{6857} 1471) 839) 71)
#{71 839 6857 1471}
Any ideas?
On Jan 13, 11:36 am, Benny Tsai benny.t...@gmail.com wrote:
(conj) will add items to different places in the collection, depending
on the type of the collection. For a set, this can be at either the
end OR the beginning.
For this problem, the output is built by:
(conj (conj (conj #{6857} 1471) 839) 71)
which is equivalent to:
(- #{6857} (conj 1471) (conj 839) (conj 71))
The innermost/first conj, (conj #{6857} 1471), sticks 1471 at the end
and produces #{6857 1471}. The next conj sticks 839 at the beginning
and produces #{839 6857 1471}. The final conj sticks 71 at the
beginning and produces the final result of #{71 839 6857 1471}.
When ordering matters, I usually use either (cons), which will always
add to the beginning regardless of the collection type, or use (conj)
with a list (will always add to the beginning) or vector (will always
add to the end).
user= (- '(6857) (conj 1471) (conj 839) (conj 71))
(71 839 1471 6857)
user= (- [6857] (conj 1471) (conj 839) (conj 71))
[6857 1471 839 71]
On Jan 13, 8:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: Question On Implicit Recursion
Replying to myself :-)
After some pondering, it DOES make sense if I pay attention to what
you guys saying: for unordered set conj can nondeterministically add
either at beginning OR end.
On Jan 13, 12:40 pm, Vitaly Peressada vit...@ufairsoft.com wrote:
Benny, thanks for your explanation. It does make sense and clarifies
the issue. What DOES NOT make sense is
Clojure 1.2.0
user= (conj (conj (conj #{4} 3) 2) 1)
#{1 2 3 4}
user= (conj (conj (conj #{6857} 1471) 839) 71)
#{71 839 6857 1471}
Any ideas?
On Jan 13, 11:36 am, Benny Tsai benny.t...@gmail.com wrote:
(conj) will add items to different places in the collection, depending
on the type of the collection. For a set, this can be at either the
end OR the beginning.
For this problem, the output is built by:
(conj (conj (conj #{6857} 1471) 839) 71)
which is equivalent to:
(- #{6857} (conj 1471) (conj 839) (conj 71))
The innermost/first conj, (conj #{6857} 1471), sticks 1471 at the end
and produces #{6857 1471}. The next conj sticks 839 at the beginning
and produces #{839 6857 1471}. The final conj sticks 71 at the
beginning and produces the final result of #{71 839 6857 1471}.
When ordering matters, I usually use either (cons), which will always
add to the beginning regardless of the collection type, or use (conj)
with a list (will always add to the beginning) or vector (will always
add to the end).
user= (- '(6857) (conj 1471) (conj 839) (conj 71))
(71 839 1471 6857)
user= (- [6857] (conj 1471) (conj 839) (conj 71))
[6857 1471 839 71]
On Jan 13, 8:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
--
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Re: Question On Implicit Recursion
On Thu, Jan 13, 2011 at 17:36, Benny Tsai benny.t...@gmail.com wrote:
(conj) will add items to different places in the collection, depending
on the type of the collection. For a set, this can be at either the
end OR the beginning.
For a (hashed) set, this can be *anywhere* (between existing elements too).
FTFY
// Ben
For this problem, the output is built by:
(conj (conj (conj #{6857} 1471) 839) 71)
which is equivalent to:
(- #{6857} (conj 1471) (conj 839) (conj 71))
The innermost/first conj, (conj #{6857} 1471), sticks 1471 at the end
and produces #{6857 1471}. The next conj sticks 839 at the beginning
and produces #{839 6857 1471}. The final conj sticks 71 at the
beginning and produces the final result of #{71 839 6857 1471}.
When ordering matters, I usually use either (cons), which will always
add to the beginning regardless of the collection type, or use (conj)
with a list (will always add to the beginning) or vector (will always
add to the end).
user= (- '(6857) (conj 1471) (conj 839) (conj 71))
(71 839 1471 6857)
user= (- [6857] (conj 1471) (conj 839) (conj 71))
[6857 1471 839 71]
On Jan 13, 8:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
--
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Re: Question On Implicit Recursion
Right, my bad. It was a typo. (sorted-set (f))
Thanks for your help.
On Jan 13, 12:16 pm, Benny Tsai benny.t...@gmail.com wrote:
Armando's suggested change worked fine for me.
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
(sorted-set f)
(conj (prime-factors (/ n f)) f
user= (prime-factors 600851475143)
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 1471 6857}
On Jan 13, 10:01 am, Vitaly Peressada vit...@ufairsoft.com wrote:
Armando, thanks for a plausible explanation. Here is what happened
after I made the suggested change:
user= (prime-factors 600851475143)
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#CompilerException java.lang.ClassCastException: java.lang.Integer
cannot be cast to clojure.lang.IFn (REPL:91)
I guess this something subtle with unordered vs. sorted-set as
implicit factors accumulator. May be that is why the author of the
solution had to use unordered set followed by (apply max ...).
On Jan 13, 11:23 am, Armando Blancas armando_blan...@yahoo.com
wrote:
A literal set is a unordered hash-set. To get the factors in order
change #{f} for (sorted-set f).
On Jan 13, 7:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
--
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Re: Question On Implicit Recursion
Good to know, thank you Ben :)
On Jan 13, 10:49 am, B Smith-Mannschott bsmith.o...@gmail.com wrote:
On Thu, Jan 13, 2011 at 17:36, Benny Tsai benny.t...@gmail.com wrote:
(conj) will add items to different places in the collection, depending
on the type of the collection. For a set, this can be at either the
end OR the beginning.
For a (hashed) set, this can be *anywhere* (between existing elements too).
FTFY
// Ben
For this problem, the output is built by:
(conj (conj (conj #{6857} 1471) 839) 71)
which is equivalent to:
(- #{6857} (conj 1471) (conj 839) (conj 71))
The innermost/first conj, (conj #{6857} 1471), sticks 1471 at the end
and produces #{6857 1471}. The next conj sticks 839 at the beginning
and produces #{839 6857 1471}. The final conj sticks 71 at the
beginning and produces the final result of #{71 839 6857 1471}.
When ordering matters, I usually use either (cons), which will always
add to the beginning regardless of the collection type, or use (conj)
with a list (will always add to the beginning) or vector (will always
add to the end).
user= (- '(6857) (conj 1471) (conj 839) (conj 71))
(71 839 1471 6857)
user= (- [6857] (conj 1471) (conj 839) (conj 71))
[6857 1471 839 71]
On Jan 13, 8:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: Monad newbie question
On Thu, Jan 13, 2011 at 3:18 AM, Saul Hazledine shaz...@gmail.com wrote: Hello, I've never used monads but I have a problem that feels like it could be solved elegantly with them. I have a sequence of functions of arbitary size and an input sequence s. Each function is given a sequence and returns a sequence that can be bigger than the input sequence. I want the output of one function to be operated on using a mapcat of the next function: (let [seq-of-fns [f1 f2 f3 ... fm]] (mapcat fm ... (mapcat f2 (mapcat f1 s))) If any of the functions return nil, I'd like the computation to stop. I don't see any real reason not to use (reduce #(if %1 (mapcat %2 %1)) s seq-of-fns) unless you have another requirement you haven't told us. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Monad newbie question
On Jan 13, 7:35 pm, Ken Wesson kwess...@gmail.com wrote: (let [seq-of-fns [f1 f2 f3 ... fm]] (mapcat fm ... (mapcat f2 (mapcat f1 s))) If any of the functions return nil, I'd like the computation to stop. I don't see any real reason not to use (reduce #(if %1 (mapcat %2 %1)) s seq-of-fns) That seems to work nicely thanks. I hadn't thought of using reduce to produce a sequence before. Saul -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Monad newbie question
Hi, depending on the length of your function sequence you might run into stack overflows, though. Just keep that in mind (or add a tactically placed doall). Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Java namespaces, Cobol, and Hierarchical file systems
On Jan 13, 2011, at 11:54 AM, Tim Daly wrote: Second, fs is using a singe segment namespace. I remember that there have been some cautions against doing that. (But not everyone agrees.) My understanding is that it's best for Java interop to have a multi-segment namespace. (Reference links below.) http://clojure.org/libs A lib name is a symbol that will typically contain two or more parts separated by periods. http://groups.google.com/group/clojure-dev/browse_frm/thread/00b1c6971c3b3394 Chas Emerick wrote: First, namespacing is good. Your foobar library won't have the same name as my foobar library -- and while you might think who else would put code in the same oddly-named namespace as mine?, it's a big world out there and an ounce of prevention is worth a pound of cure. More strictly speaking, one cannot use any class in the default package from any Java class that is in a package. That is the practical issue that leads to default package use being nonexistent in the Java space. And, you may not care about Java interop now, but either (a) you might later, or (b) your users might, now. Finally, gen-class will simply not work (last I checked) from a single-segment namespace. As a greybeard in the game, this all sounds so familiar. The point of this post is to suggest that Clojure should NOT adopt java naming conventions. ... Since lisp uses naked functions there is no natural map from functions to filenames. In sum, I'm suggesting that it isn't very lispy to use hierarchical namespace naming conventions. Just to clarify my position (it's funny to see one's self quoted out of the blue from an old thread!), I'm not at all suggesting java naming conventions when it comes to namespacing. (Although I'd note that Clojure *is* a fundamentally hosted language, and so certain idioms do flow from that host; CamelCase naming conventions for records, types, and protocols comes to mind.) No one wants to work with com.foo.bar.baz.factory.factory.factories.Factory, etc. While there is no natural mapping between functions and filenames, surely there's *some* mapping for every project that won't run afoul of the real issues that truly can crop up with single-segment namespaces[1] but still feels natural to you. Functionally logical grouping of code never goes out of style. I'd humbly submit that single-segment namespaces are a non-solution to any naming problem you'd like to solve (outside of maximal concision perhaps, which I'd suggest is a low-value problem). Cheers, - Chas [1] If you really, really don't care about host interop, and you never, *ever* will, and you're a maestro at naming projects (yup, I'm looking at you, Phil! :-), then maybe single-segment namespaces are OK. Even then, it's worth noting that even e.g. leiningen, robert hooke, etc. don't use single-segment namespaces. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Java namespaces, Cobol, and Hierarchical file systems
On Jan 13, 2011, at 3:16 PM, Chas Emerick wrote: Just to clarify my position (it's funny to see one's self quoted out of the blue from an old thread!), I'm not at all suggesting java naming conventions when it comes to namespacing. By the way, I didn't mean to put Chas on the spot. Google led me to what seemed like a good quote, and I thought he deserved the credit. Please take that as a compliment. One suggested compromise (from the old thread) was to use a short first segment so that your namespace is technically multi-segment (good for Java interop), but still short enough to be esthetically pleasing. For example, clj.foo instead of plain foo. Seems like a good compromise to me. Now, one could say that the problem is in the Clojure compiler. Maybe single segment names should be explicitly disallowed. (They're bad, don't do that.) Or maybe the compiler should silently prepend us.technomancy. to single-segment namespaces to make the world safe for Java interop with minimal danger of conflicts. That would make everybody happy. :-) Cheers, Steve -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Why is DISsoc being DIScriminated?
I noticed that although you can use assoc with sequences and vectors to modify them, you could not use dissoc to eliminate elements from them. Why is this so? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Why is DISsoc being DIScriminated?
On Thu, Jan 13, 2011 at 4:05 PM, Eduardo Julian eduardo...@gmail.comwrote: I noticed that although you can use assoc with sequences and vectors to modify them, you could not use dissoc to eliminate elements from them. Why is this so? You cannot efficiently remove items from the middle of sequences or vectors. David -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Java namespaces, Cobol, and Hierarchical file systems
On Jan 13, 2011, at 3:59 PM, Steve Miner wrote: On Jan 13, 2011, at 3:16 PM, Chas Emerick wrote: Just to clarify my position (it's funny to see one's self quoted out of the blue from an old thread!), I'm not at all suggesting java naming conventions when it comes to namespacing. By the way, I didn't mean to put Chas on the spot. Google led me to what seemed like a good quote, and I thought he deserved the credit. Please take that as a compliment. I did, thanks. :-) One suggested compromise (from the old thread) was to use a short first segment so that your namespace is technically multi-segment (good for Java interop), but still short enough to be esthetically pleasing. For example, clj.foo instead of plain foo. Seems like a good compromise to me. That seems perfectly fine, as long as the prefix or suffix isn't standard -- otherwise, for purposes of runtime differentiation, such namespaces are functionally a single segment. i.e. if the standard is clj.foo or baz.core, then someone else's clj.foo or baz.core will conflict just as well. FWIW, I use cemerick as a prefix for all personal stuff (though I do little programming that is both personal and significant enough to warrant worrying about namespaces). I assume that everyone has their preferred irc/IM/email handle; using it as a prefix seems reasonable to me, anyway. If your name changes, then modifying some namespaces is surely not the most difficult part of that process! - Chas -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Enhanced Primitive Support Syntax
Hi all, I've been reading about the changes to Clojure that are occurring with regards to improving performance of arithmetic operations. For example, + no longer auto promotes and +' has been introduced as an auto-promoting addition operator. The idea of introducing additional syntax is a bit odd to me, so I had thought that it could be solved by setting an environmental variable for the namespace and the use of macros. For example, maybe set *enhanced-primitive-support* true or false will determine the behavior of the operators (+, -, etc.) for an entire namespace. If a user wants a different set of behaviors for a block of code in that namespaces, they could wrap the code in a macro called something like enhanced-primitive-support or old-primitive-support: (enhanced-primitive-support (+ a b) ) I was wondering why an approach like this was not taken? Thanks, RJ -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Why is DISsoc being DIScriminated?
On Thu, Jan 13, 2011 at 4:05 PM, Eduardo Julian eduardo...@gmail.com wrote:
I noticed that although you can use assoc with sequences and vectors
to modify them
I get an exception trying to assoc a sequence in 1.2.
you could not use dissoc to eliminate elements from
them. Why is this so?
Deletion in the middle is not easy with lists or vectors. (Interesting
that (dissoc '(1 2 3) 0) and (dissoc [1 2 3] 2) don't work, though;
(assoc [1 2 3] 3 4) works to extend by one so why not allow dissoc to
contract by one? Although it would just be synonymous with pop. And
(assoc '(1 2 3) 0 7) doesn't work, though (cons 7 '(1 2 3)) would do
the same thing anyway, and (rest '(1 2 3)) the same as (dissoc '(1 2
3) 0).)
Treating a vector as a map from integers to objects, perhaps dissoc
could quasi-work on vectors by having (dissoc v n) act like (assoc v n
nil); then again, it wouldn't cause (contains? v n) to go from true to
false, which people might want from dissoc.
It's probably best to leave things as they are. Need to shorten by
one? Use pop (vectors) or rest (lists). Need to really dissoc? Use a
sparse vector, that is, an actual map with integer keys, like {0 1,
1 2, 2 3} instead of [1 2 3].
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Re: [ANN] fs - file system utilities for Clojure
First, I suggest that you look at the standard clojure.java.io package for some useful functions that are already in Clojure 1.2. In particular, you could use io/file instead of (File. xxx) in your code to add some flexibility to the kinds of things that can be treated as a file. I think io/file could replace your fs/join. Also, io/copy is very flexible so it's worth a look, too. Yeah, I wasn't aware of the many things in clojure.java.io (used just reader from there). I do plan switch to clojure.java.io soon. Second, fs is using a singe segment namespace. I remember that there have been some cautions against doing that. (But not everyone agrees.) My understanding is that it's best for Java interop to have a multi-segment namespace. (Reference links below.) (and many other mails in this thread). Coming from a Python background, single segment namespaces are natural to me and have never been a problem. I added :gen-class and ran lein compile and it worked, so I don't see a problem here as well. Changing it to com.mikitebeka.fs or lazy1.fs has too much of an ego trip for me :) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Why is DISsoc being DIScriminated?
The result of `assoc` on a vector is well-defined, by treating the vector as a map with integer indices as keys. But the result of `dissoc` on a vector is not so clear. `dissoc` removes a key from an associative thing. But you can't remove an index from the middle of a vector. Even if you could efficiently remove a single value, the index still exists, with a different value. In short, the definition of `dissoc` makes it impossible on a vector. Some other data structures, such as finger trees [1], support efficient insertion and removal from the middle, but it's still not a `dissoc` operation. Sequences in general support neither `assoc` nor `dissoc`. [1] https://github.com/clojure/data.finger-tree -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Enhanced Primitive Support Syntax
The goal of primitive math is better performance in the common case. The implementation makes the assumptions that Java long is big enough for nearly all cases, and that auto-promotion to BigInteger (and the resulting performance hit) is rarely desirable. The + function still promotes, it just promotes everything to long or double. If you want BigInts or BigDecimals, just insert one of them into the calculation, and everything else will get promoted to BigInt or BigDecimal. The only difference between + and +' is that +' will promote to BigInt if you overflow a long, whereas + will thrown an exception. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Enhanced Primitive Support Syntax
On Thu, Jan 13, 2011 at 7:28 PM, Stuart Sierra the.stuart.sie...@gmail.com wrote: The goal of primitive math is better performance in the common case. Of course, this better performance is not needed in the common case, IMO, but only in hotspots that do number crunching, where people already optimize using primitive locals, coercion, and unchecked-foo. The implementation makes the assumptions that Java long is big enough for nearly all cases It also makes the assumption that the Java long is as fast as native arithmetic. Which, on a lot of 32-bit hardware, it won't be. and that auto-promotion to BigInteger (and the resulting performance hit) is rarely desirable. Debatable. I, for one, prefer to have unadorned arithmetic be correct at the expense of a little speed, while still having a way to get the speed in performance-critical parts of my code. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Clojure regexs
So I am converting some Ruby code I have into CLojure for practice/fun and I
am having trouble finding info via Google.
I want to take something like this from Ruby and do it in Clojure:
DATE_REGEX = /^\s*(\d{4})\s+(\d{1,2})\s+(\d{1,2})/
token =~ DATE_REGEX
[$1, $2, $3]
So far my best guess has been:
(defonce date-regex #^\s*(\d{4})\s+(\d{1,2})\s+(\d{1,2}))
(re-find date-regex line)
but I'm not sure how to access $1, $2, and $3
Another example I'd like to convert is this:
DAYS_OF_WEEK_REGEX = /^\s*(#{Date::DAYS_OF_WEEK.join('|')})/i
token =~ DAYS_OF_WEEK_REGEX
$1.downcase.to_sym
Best attempt is:
(defonce days-of-week-regex #mon|tue|wed|thu|fri|sat|sun(?i))
(re-find days-of-week-regex line)
Here I'd love to know the syntax for ignore-case, along with how to access $1.
Thanks,
Alex
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Re: Clojure regexs
So I am converting some Ruby code I have into CLojure for practice/fun and I am having trouble finding info via Google. Clojure uses the same regex style as Java, so you'll need to search for information on Java regexes rather than Clojure regexes. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
Here is one way: user= (import 'java.util.regex.Pattern) java.util.regex.Pattern user= (def p (Pattern/compile mon|tue|wed|thu|fri|sat|sun Pattern/CASE_INSENSITIVE)) #'user/p user= (re-find p I have a dentist appoint on Monday morning, so you'll need to take the kids to school.) Mon Bill On Thursday, January 13, 2011 8:35:17 PM UTC-6, Alex Baranosky wrote: Here I'd love to know the syntax for ignore-case -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
i think you want to do something like this: (let [_ year month day] (re-find date-regex line)) On Thu, Jan 13, 2011 at 8:50 PM, Eric Lavigne lavigne.e...@gmail.com wrote: So I am converting some Ruby code I have into CLojure for practice/fun and I am having trouble finding info via Google. Clojure uses the same regex style as Java, so you'll need to search for information on Java regexes rather than Clojure regexes. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
I see. So I may have to use some kind of clunky syntax instead of a nice $1, $2, $3 syntax. I can handle that I guess :) Thanks. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
A blog entry I read (and now can't find) mentioned being able to use syntax like (?i) to do the ignore case. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
For accessing groups in a match, you can use (re-matches). It will
always give the full match as the first element though:
user= (re-matches date-regex 2011 1 13)
[2011 1 13 2011 1 13]
So to replicate the Ruby code's behavior maybe you'll just want (rest
(re-matches date-regex line)).
For ignoring case, putting (?i) at the beginning of the regex worked
for me. (re-find) should give you $1 just fine.
user= (require '[clojure.string :as str])
nil
user= (str/lower-case (re-find #(?i)mon|tue|wed|thu|fri|sat|sun
asdf MON tue))
mon
Hope this helps!
On Jan 13, 7:35 pm, Alex Baranosky alexander.barano...@gmail.com
wrote:
So I am converting some Ruby code I have into CLojure for practice/fun and I
am having trouble finding info via Google.
I want to take something like this from Ruby and do it in Clojure:
DATE_REGEX = /^\s*(\d{4})\s+(\d{1,2})\s+(\d{1,2})/
token =~ DATE_REGEX
[$1, $2, $3]
So far my best guess has been:
(defonce date-regex #^\s*(\d{4})\s+(\d{1,2})\s+(\d{1,2}))
(re-find date-regex line)
but I'm not sure how to access $1, $2, and $3
Another example I'd like to convert is this:
DAYS_OF_WEEK_REGEX = /^\s*(#{Date::DAYS_OF_WEEK.join('|')})/i
token =~ DAYS_OF_WEEK_REGEX
$1.downcase.to_sym
Best attempt is:
(defonce days-of-week-regex #mon|tue|wed|thu|fri|sat|sun(?i))
(re-find days-of-week-regex line)
Here I'd love to know the syntax for ignore-case, along with how to access $1.
Thanks,
Alex
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Re: Clojure regexs
On Thu, Jan 13, 2011 at 9:54 PM, Alex Baranosky alexander.barano...@gmail.com wrote: I see. So I may have to use some kind of clunky syntax instead of a nice $1, $2, $3 syntax. I can handle that I guess :) Hey, it's a Lisp! You can use almost any syntax you want. How about %1, %2, %3: (defn re-do [f regex input] (apply f (rest (re-find regex input (re-do #(do-stuff-with %3 %1 %2) regex input) Or even (defmacro re-let [names regex input body] `(let [[_ ~@names] (re-find ~regex ~input)] ~@body)) (re-let [year month day] date-regex line (do-something-with year month day)) This one doesn't even have the bug that gaz jones's let has. ;) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure Quizzes?
They do seem to allow whatever you like if you upload your own package. I'm hooked on using their built-in editor, so in some cases I copy-and-paste code until they get around to updating their version of Clojure. The one nice thing about the site is that they do seem rather responsive to questions, bugs and feature requests! I'm jsvazic on the site if anyone is interested. :-) Based on the list of recent submissions lately, it seems like Clojure is getting a lot of exposure! It's funny to see some language turf wars showing up, since I've seen Clojure dominate recent submissions list, then Scala gets a kick, then people go on a PHP binge for some reason. :-) In any case, I'm finding the site absolutely great, and it's been an absolute boon for updating my Clojure skills. I fully expect that in the next 6 months I'll look back at earlier submissions and say what was I thinking?! :-) On Jan 13, 2:50 am, Robert McIntyre r...@mit.edu wrote: They seem to allow you to include anything in a lib directory that you'd want. I sometimes include apache commons-io and clojure-contrib1.2 without any problems. I also included a sql connection library for one of the problems, so it seems fine :) --Robert McIntyre On Thu, Jan 13, 2011 at 2:00 AM, Stuart Campbell stu...@harto.org wrote: On 12 January 2011 14:07, Robert McIntyre r...@mit.edu wrote: You can use the latest version of clojure if you include it as a dependency in your submission, so even though they say they only support clojure1.0 they really support all of them. Are other 3rd-party libs allowed, too? Cheers, Stuart -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure Quizzes?
On Thu, Jan 13, 2011 at 10:04 PM, John Svazic jsva...@gmail.com wrote: They do seem to allow whatever you like if you upload your own package. I'm hooked on using their built-in editor, so in some cases I copy-and-paste code until they get around to updating their version of Clojure. The one nice thing about the site is that they do seem rather responsive to questions, bugs and feature requests! I'm jsvazic on the site if anyone is interested. :-) Based on the list of recent submissions lately, it seems like Clojure is getting a lot of exposure! It's funny to see some language turf wars showing up, since I've seen Clojure dominate recent submissions list, then Scala gets a kick, then people go on a PHP binge for some reason. :-) PHP? Isn't that a web page generation engine, rather than a general-purpose application programming language? In any case, I'm finding the site absolutely great, and it's been an absolute boon for updating my Clojure skills. I fully expect that in the next 6 months I'll look back at earlier submissions and say what was I thinking?! :-) I think we all get that at first. It may be because functional/Lisp is somewhat alien to most other things you're likely to have had experience with beforehand, or just because C++ is to chess as Lisp is to go -- fewer moves and simpler rules, but oh so much depth as your Lisp-fu grows strong. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
bah! good catch. (let [[_ year month day]] (re-find date-regex line)) fixed! On Thu, Jan 13, 2011 at 9:03 PM, Ken Wesson kwess...@gmail.com wrote: On Thu, Jan 13, 2011 at 9:54 PM, Alex Baranosky alexander.barano...@gmail.com wrote: I see. So I may have to use some kind of clunky syntax instead of a nice $1, $2, $3 syntax. I can handle that I guess :) Hey, it's a Lisp! You can use almost any syntax you want. How about %1, %2, %3: (defn re-do [f regex input] (apply f (rest (re-find regex input (re-do #(do-stuff-with %3 %1 %2) regex input) Or even (defmacro re-let [names regex input body] `(let [[_ ~@names] (re-find ~regex ~input)] ~@body)) (re-let [year month day] date-regex line (do-something-with year month day)) This one doesn't even have the bug that gaz jones's let has. ;) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
On Thu, Jan 13, 2011 at 10:22 PM, gaz jones gareth.e.jo...@gmail.com wrote: bah! good catch. (let [[_ year month day]] (re-find date-regex line)) fixed! Oh, gaz. I'm so so sorry. :( -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure regexs
lol oh noes! i should really stop doing this while watching 30rock... On Thu, Jan 13, 2011 at 9:38 PM, Ken Wesson kwess...@gmail.com wrote: On Thu, Jan 13, 2011 at 10:22 PM, gaz jones gareth.e.jo...@gmail.com wrote: bah! good catch. (let [[_ year month day]] (re-find date-regex line)) fixed! Oh, gaz. I'm so so sorry. :( -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Clojure in Small Pieces
The latest version of Clojure in Small Pieces is up. http://daly.axiom-developer.org/clojure.pamphlet http://daly.axiom-developer.org/clojure.pdf A few people have volunteered to write sections. More volunteers are welcome. There are new sections. The LispReader is split apart and is undergoing documentation. The index now covers all of the classes and interfaces with hyperlinks to the defining pages. The Appendix A has external hyperlinks to browser pages describing standard Java classes that are referenced by the code. There are some graphics for bit-partitioning and red-black trees. And, on a technical note, the clojure.sty file is no longer needs as I rewrote the latex macros. Tim Daly P.S. the tangle.c code is still up on the website at: http://daly.axiom-developer.org/tangle.c although you don't need it as it is in the pamphlet. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure Quizzes?
As HTML-y as it it is, PHP is Turing complete and thus a real programming language. It's got foreach loops, mutable arrays, and boolean logic, and that's one particular set of operations to simulate a Turing machine. http://en.wikipedia.org/wiki/Turing_machine http://aturingmachine.com/ sincerely, --Robert McIntyre On Thu, Jan 13, 2011 at 10:07 PM, Ken Wesson kwess...@gmail.com wrote: On Thu, Jan 13, 2011 at 10:04 PM, John Svazic jsva...@gmail.com wrote: They do seem to allow whatever you like if you upload your own package. I'm hooked on using their built-in editor, so in some cases I copy-and-paste code until they get around to updating their version of Clojure. The one nice thing about the site is that they do seem rather responsive to questions, bugs and feature requests! I'm jsvazic on the site if anyone is interested. :-) Based on the list of recent submissions lately, it seems like Clojure is getting a lot of exposure! It's funny to see some language turf wars showing up, since I've seen Clojure dominate recent submissions list, then Scala gets a kick, then people go on a PHP binge for some reason. :-) PHP? Isn't that a web page generation engine, rather than a general-purpose application programming language? In any case, I'm finding the site absolutely great, and it's been an absolute boon for updating my Clojure skills. I fully expect that in the next 6 months I'll look back at earlier submissions and say what was I thinking?! :-) I think we all get that at first. It may be because functional/Lisp is somewhat alien to most other things you're likely to have had experience with beforehand, or just because C++ is to chess as Lisp is to go -- fewer moves and simpler rules, but oh so much depth as your Lisp-fu grows strong. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Clojure Quizzes?
On Fri, Jan 14, 2011 at 1:13 AM, Robert McIntyre r...@mit.edu wrote: As HTML-y as it it is, PHP is Turing complete and thus a real programming language. So are LaTeX, Javascript, and a few others, but from what I've seen they're all meant for specific purposes rather than general-purpose software engineering. It's got foreach loops, mutable arrays, and boolean logic, and that's one particular set of operations to simulate a Turing machine. I read somewhere that it suffices to have a program counter, a register, four stacks, jump-back-or-forth-N-steps with a small bounded N, if register zero then next instruction otherwise skip one instruction, increment register (which wraps at some value), and peek or pop for each of the four stacks (to the register). Alternatively, a program counter, a stack, a cursor into an infinite deque, and these eight instructions: increment at cursor, decrement at cursor, jump amount at cursor, if zero at cursor next instruction else skip, cursor left one, cursor right one, push program counter, pop program counter. The universal Turing machine concept suggests that there's an instruction set for which only the infinite deque is needed, with cursor-left, cursor-right, and some additional instructions, but no long range jumps within the deque, and instructions also fetched from the deque with no separate program counter. It would be a real bitch to program, though. The general rule seems to be that a) there has to be at least one if-something condition that alters flow, say by optionally skipping one instruction that can be a longer-range jump and may be followed by another such; b) there has to be a backward jump possibility; and c) there has to be some kind of memory -- either bidirectionally infinite and cursor-navigable like a giant ArrayList, or at least four stacks that can be separately peeked and popped. With just one stack you can apparently get a big subset of fully general computation but not the whole deal. There also has to be d) arithmetic of some kind, on the memory content and interacting in some way with the if condition. http://en.wikipedia.org/wiki/Turing_machine http://aturingmachine.com/ I see your Turing machine and raise you this: http://www.rezmason.net/wireworld/ -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
