On Sun, Nov 13, 2011 at 10:46 AM, Jules wrote:
> Here is a slight modification of the previous program that can be
> executed in two directions:
>
> N = [40]
> A = range(1,40)
> B = range(1,40)
> C = range(1,40)
> D = range(1,40)
>
> def valid(a,b,c,d,n):
> weights = set(w*a+x*b+y*c+z*d for w
So, if one stays in the imperative world, why not just the generic problem
instead of the specific one ?
This clojure solution can solve the problem for any N (total weight) and
any M (any number of parts the stone can be spit into):
https://gist.github.com/1332020
The implementation is a bit lo
Here is a slight modification of the previous program that can be
executed in two directions:
N = [40]
A = range(1,40)
B = range(1,40)
C = range(1,40)
D = range(1,40)
def valid(a,b,c,d,n):
weights = set(w*a+x*b+y*c+z*d for w in [-1,0,1]
for x in [-1,0,1]
checko and subchecko work together to determine whether an ordered set of
weights can produce integers 1 to 40 in reverse. It's more verbose since we
are preserving the ability to run our program backwards - which is simply a
byproduct of writing a purely relational program.
I'm curious if it can
I'll just clarify, the "matches" function body jumps out at me. "checko"
doesn't, but it's role in the problem is still clear, even if its
implementation is not. I think that's still an important trait.
Can checko be improved? I'm not sure. What does subchecko do, David?
Ambrose
On Sun, Nov 13,
"Understandability" is subjective. The meaning of the cKanren really jumps
out at me, the python program takes a lot more for me to think through.
There is nothing wrong with pruning the search space in this program. As
you said, doing so reduced the Python program execution time to 2ms!
Ambrose
Write a version in Python that can infer 40 from the inputs then maybe we
can talk about declarative. I have no idea what you mean by "cheating" and
even less of an idea what you mean by "nice."
On Saturday, November 12, 2011, Jules wrote:
> The time difference is largely due to using the product
The time difference is largely due to using the product library
function instead of for comprehensions and the fact that the cKanren
version cheats by hardcoding part of the solution, and hardcoding an
extra constraint alldiff(a,b,c,d). The following code takes ~12ms with
PyPy on my computer:
def
Also note that even given all this generality over the Python code - the
earlier Python implementation takes ~300ms and this implementation takes
>900ms on my machine.
Quite a bit slower than ~12ms. Inferring 40 takes even less time of course
- ~8ms.
But really the execution time is just icing on
Excellent point Ambrose ;) And here it is:
(define (subchecko w sl r o n)
(conde
((== sl ())
(fresh (a d)
(domfd a (range 1 100))
(conde
((conso a d r) (plusfd a 1 w)
(conso w r o))
((== r '()) (conso w r o)
((fresh (a b c
I assume the cKanren version can run backwards with a little tweak?
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(define (matches n)
(run #f (q)
(fresh (a b c d s1 s2)
(== q `(,a ,b ,c ,d))
(domfd a b c d s1 s2 (range 1 n))
(all-differentfd `(,a ,b ,c ,d))
(== a 1)
(<=fd a b) (<=fd b c) (<=fd c d)
(plusfd a b s1) (plusfd s1 c s2) (plusfd s2 d n)
(checko `
Can you reorder your statements without changing the meaning of your
program? For example you cannot move the placement of the "return"
expression.
David
On Fri, Nov 11, 2011 at 8:09 PM, Jules wrote:
> Here is a new program. Perhaps you would consider this declarative:
>
> def valid(a,b,c,d):
>
Here is a new program. Perhaps you would consider this declarative:
def valid(a,b,c,d):
weights = set(w*a+x*b+y*c+z*d for (w,x,y,z) in
product([-1,0,1],repeat=4))
return weights >= set(range(1,41))
ws = [(a,b,c,d) for (a,b,c,d) in product(range(1,41),repeat=4)
if a <= b <=
Are we reading the same cKanren code? I'll give you that the matches
definition is declarative, but then read checko and subchecko. They
are all about (recursive) control flow. Where does the specification
say anything remotely close to the checko and subchecko relations? In
contrast to this, the P
> My Python code is much more declarative than the given
> cKanren code in that regard. Just compare:
> http://dosync.posterous.com/another-taste-of-ckanren
I don't think you understand what declarative programming is at its
core. Declarative programming
To borrow from the ever-present wikipedi
In the same way the cKanren version is syntactic sugar around
imperative code. Declarative is not a property of a language, it's a
property of code that says how close to a mathematical specification
the code is. My Python code is much more declarative than the given
cKanren code in that regard. Ju
>I wonder if you can make the cKanren version just as declarative as
>this one (cKanren's purpose being declarative).
I don't think the Python version could be considered declarative. One
of the concepts behind logic
programming (and to some extent declarative programming) is that you
can simply p
Here is a Python version (http://pastebin.com/reW5eaCy):
def valid(a,b,c,d):
return set(w*a + x*b + y*c + z*d
for w in [-1,0,1]
for x in [-1,0,1]
for y in [-1,0,1]
for z in [-1,0,1]) > set(range(1,41))
ws = [(a,b,c,d) for a in range(
A blog post explaining the solution step by step
http://dosync.posterous.com/another-taste-of-ckanren.
On Mon, Oct 31, 2011 at 9:36 PM, David Nolen wrote:
> Here's a correct version that solves the puzzle in ~12ms,
> https://gist.github.com/1329580. A bit longer but it fun to combine
> constrain
Here's a correct version that solves the puzzle in ~12ms,
https://gist.github.com/1329580. A bit longer but it fun to combine
constraints w/ search.
Will try to find some time to write a more detailed explanation.
On Sun, Oct 30, 2011 at 9:00 PM, David Nolen wrote:
> Heh, as someone pointed out
Wow!
Shows off the advantages of embedding in a language like Scheme too.
I'm planning to join you in the implementation in core.logic after
November. Keep me (us) posted :)
Would CLP be more useful for a predicate dispatch implementation than what
core.logic provides currently?
Ambrose
On Mon
Heh, as someone pointed out this doesn't actually solve the puzzle since
I'm not considering putting stones on either side of the scale. Still I
think the idea of what cKanren can do is communicated :)
On Sun, Oct 30, 2011 at 8:34 PM, Brent Millare wrote:
> Looks really cool. Can't wait to see th
Looks really cool. Can't wait to see the talk.
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To u
Larent Petit pointed out this fun challenge:
http://beust.com/weblog/2011/10/30/a-new-coding-challenge/
To get a sense of how cool cKanren and constraint logic programming is I
recommend reading my post about solving it using cKanren
http://dosync.posterous.com/a-taste-of-ckanren.
This is what Wi
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