CSVErrors in the following syntax
is a bound type variable:
implement {CSVErrors} extfree(errs) = ...
What you need is
implement extfree<CSVErrors>(errs) = free(errs)
On Tuesday, March 14, 2017 at 9:35:36 AM UTC-4, August Alm wrote:
>
> Great application of "reassume"! =D I had to reinstall ATS2 to make the
> new syntax available and now I've had a go at it.
> can compile the "reassume"-example with [int2_t0ype] that you posted on
> this list, so my reinstallation is working.
> However, I don't seem to understand how to use "reassume" properly. If I
> type
>
> absvtype CSVErrors
> local assume CSVErrors = List0_vt(CSVError) in (* nothing *) end
>
> implement {CSVErrors} extfree(errs) =
> let reassume CSVErrors
> in case errs of
> | ~list_vt_nil() => ()
> | ~list_vt_cons(er, ers1) => extfree<CSVErrors>(ers1)
> end
>
> then I get an error saying "the identifier [CSVErrors] does not refer to a
> static constant". Adding [vtypedef CSVErrors = CSVErrors] or
> [stadef CSVErrors = CSVErrors] after the initial "absvtype" declaration
> does not alleviate the problem. What's wrong?
>
> Den tisdag 14 mars 2017 kl. 02:39:44 UTC+1 skrev gmhwxi:
>>
>>
>> Please first do this:
>>
>> (*
>> vtypedef
>> CSVErrors = List0_vt(CSVError)
>> *)
>> absvtype CSVErrors
>> local
>> assume CSVErrors = List0_vt(CSVError)
>> in (*nothing*) end
>>
>> Whenever you need the definition of CSVErrors, please do 'reassume
>> CSVErrors' in the
>> scope where you need it. For instance, I modified some of your code as
>> follows:
>>
>> implement {} validate(rs: CSVTable): CSVResult =
>> let
>> reassume CSVErrors
>> in
>> $ldelay(
>> case !rs of
>> | ~nil() => let
>> val nodata = list_vt_make_sing(No_Data()): CSVErrors
>> in Left(nodata) :: empty()
>> end
>> | ~stream_vt_cons(r, rs1) => let
>> val length_r = list_vt_length(r)
>> implement {} current_length() = length_r
>> in extract_errs(r) :: stream_vt_usermap(rs1, extract_errs)
>> end
>> ,
>> ~rs
>> )
>> end
>>
>> After this, your code should be running, and hopefully, running correctly
>> :)
>>
>>
>>
>>
>> On Mon, Mar 13, 2017 at 9:09 PM, Hongwei Xi <[email protected]> wrote:
>>
>> This is because CSVErrors is a dependent type.
>>
>> The right way to do it is to make CSVErrors abstract.
>>
>> If you are using ATS2-0.3.3, then you can use the feature of 'reassume'.
>> I will show you how to do it in another message.
>>
>>
>> On Mon, Mar 13, 2017 at 8:10 PM, August Alm <[email protected]> wrote:
>>
>> If I write
>>
>> implement extfree<CSVErrors> = ...
>>
>> then I get it passed the typechecking level of compilation, but when
>> trying to generate C-code I instead get an error saying [extfree] has not
>> been implemented:
>>
>> "csv_lexer_dats.c:93504:45: error: ‘extfree’ undeclared (first use in
>> this function)"
>>
>>
>>
>> Den tisdag 14 mars 2017 kl. 00:57:18 UTC+1 skrev August Alm:
>>
>> Yes, as you guessed I am having problems with covariance. Some I have
>> solved but this one leaves me very puzzled:
>>
>> I'll copy the code here in the order that it appears in my file. First
>> (in "csv_lib.hats", which is #include:d at the very beginning) I have a
>> template
>>
>> extern fun {a: vt0ype} extfree(x: a): void
>>
>> which is used to free variables in some of the functions using the
>> [Either] constructor. Then I have:
>>
>> vtypedef CSVErrors = List0_vt(CSVError)
>>
>> where CSVError is a non-linear datatype. If I after that definition write
>>
>> implement {CSVErrors} extfree(errs) = list_vt_free(errs),
>>
>> then I get a compiler error telling me that [CSVErrors] can't be assigned
>> the type of linear lists. If I try to go explicit and write
>>
>> implement{CSVErrors} extfree(errs) = let
>> val errs: List0_vt(CSVError) = errs
>> in case errs of
>> | ~list_vt_nil() => ()
>> | ~list_vt_cons(er, ers1) => extfree<CSVErrors>(ers1)
>> end
>>
>> then I get roughly the same error, saying:
>>
>> The actual term is: S2Evar(CSVErrors(8927))
>> The needed term is: S2Eapp(S2Ecst(list_vt0ype_int_vtype);
>> S2Ecst(CSVError), S2EVar(5476))
>>
>> How can I help the compiler infer that CSVErrors is indeed a
>> listvt0ype_int_vtype of CSVError?
>>
>> Den måndag 13 mars 2017 kl. 23:42:03 UTC+1 skrev gmhwxi:
>>
>> Once INV annotation is done properly, template annotation can be pretty
>> much removed.
>>
>>
>> On Mon, Mar 13, 2017 at 6:39 PM, August Alm <[email protected]> wrote:
>>
>> Thanks for the hint! I added template arguments wherever I could and now
>> I got some error messages that actually say something. However, I do find
>> it a bit disconcerting that the compiler would segfault rather than tell me
>> I need to annotate templates.
>>
>> Den måndag 13 mars 2017 kl. 22:02:57 UTC+1 skrev gmhwxi:
>>
>> I will take a look later. Based on your description, the issue
>> seems to be caused by not providing certain template arguments
>> explicitly:
>>
>> Say, foo is a template. Please use foo<...>(...) instead of foo(...)
>>
>> Compared to Haskell, type inference in ATS is quite limited :)
>>
>> On Mon, Mar 13, 2017 at 4:51 PM, August Alm <[email protected]> wrote:
>>
>> So... I added some "second stage" parsing functionality, to get the en
>> result in tabular form rahter than as a single [stream_vt], and to check
>> for global errors such as unequal number of columns in the rows, and now I
>> am back to segfaulting! =( However, this time it does not seem to be a
>> stack issue because I run into the segmentation fault already at the
>> compilation stage.
>>
>> I code in Vim and have it set up so that typing ":make" will run "patsopt
>> -tc -d %", i.e., typechecking only. When I do everything seems fine--no
>> complaints. I have used this utility for some time now and it has always
>> worked like a charm. Wierdly though, if I issue "$ patsopt -tc -d
>> csv_lexer.dats" in the console instead I get a segfault. The same happens
>> for every other compilation command: I've tried compiling just using type
>> checking, just to c, or etc. Always segfault. Compiling with the "-verbose"
>> flag prints
>>
>> exec(patsopt --output csv_lexer_dats.c --dynamic csv_lexer.dats)
>> Segmentation fault
>> exec(patsopt --output csv_lexer_dats.c --dynamic csv_lexer.dats) = 35584
>>
>> which does not tell me anything.
>>
>> My code can be found at https://github.com/August-Alm/ats_csv_lexer Note
>> that I have moved some function implementations into a hats-file. Might
>> this be a cause of trouble? Any tips at all on how to debug this are most
>> appreciated. I don't know where to even begin as gdb seems useless as long
>> as I can't even generate the C-code.
>>
>> Best wishes,
>> August
>>
>> Den onsdag 8 mars 2017 kl. 23:44:10 UTC+1 skrev gmhwxi:
>>
>> >>I take that as being somewhat tongue-in-cheek. ATS is a very
>> theoretical language, after all.
>>
>> I know that this sounds very ironic but interesting stuff often does
>> sound ironic :)
>>
>> My view of programming language research is changing gradually but
>> surely. I now strongly feel
>> that the most important programming support is to facilitate the need to
>> alter/adapt the behaviour
>> of a written program without actually requiring direct changes to be made
>> to the program. And the
>> template system of ATS can be seen as an attempt to provide programming
>> support of this sort.
>>
>>
>> On Wed, Mar 8, 2017 at 4:47 PM, August Alm <[email protected]> wrote:
>>
>> See in.
>>
>> Den onsdag 8 mars 2017 kl. 17:51:36 UTC+1 skrev gmhwxi:
>>
>> Tangential to the topic of monads: Do you know if someone has thought
>> about the relations between ATS and "enriched effect calculus" (as
>> described in http://homepages.inf.ed.ac.uk/als/Research/Sources/eec.pdf)
>> or "linear state monads" (as mentioned in
>> https://arxiv.org/pdf/1403.1477.pdf)? There is a clear analogy.
>> Implementing a concept such as a linear state monad in ATS would be nice, I
>> think. Monadic programming on an Arduino, anyone? =) It would certainly be
>> a unique selling point.
>>
>>
>> I can't really follow these monad papers. Too much for me :)
>> Given your background, maybe you could give this a try?
>>
>> I'm tempted but I feel like I have to understand ATS:s function tags
>> ("cloref" and the like, the flavours of function) better first, and
>> generally get a more solid footing. I don't want to write something "cool",
>> I want it to be useful, too.
>>
>>
>> Over the years, I have gradually grown more and more cynic about
>> "theoretic" research
>> in the area of programming languages. I feel that the most urgent issue
>> in programming is
>> to find effective approaches to reducing programming complexity.
>>
>> I take that as being somewhat tongue-in-cheek. ATS is a very theoretical
>> language, after all. To clarify, I think Haskell suffers greatly from
>> having too little focus on efficiency (among many of its users, not among
>> the guys working on the compiler). I heard about ATS about the same time as
>> I heard about Idris (the dependent type thing) and decided to pursue ATS
>> precisely because of its air of efficiency and "real-world-readiness". I do
>> still love my Haskell though, mainly because it is so easy to be productive
>> with it. Scala has a very good no-bs culture and good library hygiene, but
>> I'm not too fond of OOP so...
>>
>>
>> For instance, in your csv parser, there are a lot of if-then-else's.
>> Maybe you took them from
>> some Haskel code. The point is that if-then-else's make programming hard
>> to write and harder
>> to read/follow. I propose the following style:
>>
>> I first tried to write it using only pattern matching but failed to get
>> it passed the typechecker. Maybe I will have another go at it.
>>
>>
>> 1) Implementing a csv parser without worrying about quotes (DQUOT). Call
>> this version 1.
>> 2) Using templates to improve version 1 without directly modifying
>> version 1. Another way
>> to put it: you still have version 1 available after doing the
>> improvement.
>>
>> If I was uncertain about the algorithm then such an incremental
>> development style would surely be preferable, but since the code is a port
>> of a tried and tested Haskell library I'm
>> not very motivated to scrap and start over. But for my next project(s) I
>> will try to heed your words.
>>
>> I know that this may sound a bit vague but that is my point. Being vague
>> makes people
>> think more and more deeply :)
>>
>> Cheers!
>>
>>
>> On Tuesday, March 7, 2017 at 4:52:58 PM UTC-5, August Alm wrote:
>>
>> I'm glad too! I wrote my first "Hello World" program (in Haskell) less
>> than four months ago, before that I was completely illiterate about
>> programming--writing a linear, lazy CSV-parser in ATS has definitely been
>> my most challenging venture so far. I mean this in a good way. ATS is
>> quickly becoming my favorite language. It is daunting at times, sure, but
>> its unique combination of low-level abilities and functional abstractions
>> makes me feel like the Star Trek idiom "To boldly go where no one has gone
>> before", heh. The ATS sky is so vast I've almost forgot about monads. And
>> YES!, I do suggest trying ATS to every programmer I meet.
>>
>> Tangential to the topic of monads: Do you know if someone has thought
>> about the relations between ATS and "enriched effect calculus" (as
>> described in http://homepages.inf.ed.ac.uk/als/Research/Sources/eec.pdf)
>> or "linear state monads" (as mentioned in
>> https://arxiv.org/pdf/1403.1477.pdf)? There is a clear analogy.
>> Implementing a concept such as a linear state monad in ATS would be nice, I
>> think. Monadic programming on an Arduino, anyone? =) It would certainly be
>> a unique selling point.
>>
>> I do not understand what you're aiming at with your suggestion to maje
>> CSVState a datavtype or absvtype. Could you elaborate? I have seen abstract
>> types used as a way to make otherwise allowed operation illegal (there is
>> an example in your book, I think, of how to construct a record type where
>> some fields are mutable and some are not), but not for the sake of
>> overloading symbols.
>>
>> I will rewrite the code so that DELIM and QNLIN are passed as templates.
>> I also intend to add some further functionality, like functions for
>> filtering out errors, for printing and for collecting the output in tabular
>> form with rows and columns rather than as a single row. When I'm satisfied
>> I will make an npm-package out of it.
>>
>> Best wishes,
>> August
>>
>> Den tisdag 7 mars 2017 kl. 02:21:00 UTC+1 skrev gmhwxi:
>>
>> Really glad that you got it to work!
>>
>> I suggest that you make a npm-package for the parser and then
>> publish the package. In this way, other ats-lang users can benefit
>> from your work easily.
>>
>> You could try to introduce some abstract types into your code. For
>> instance, I would suggest that you make CSVstate a datavtype (linear
>> datatype)
>> (a datatype is often referred to as being semi-abstract). Then you can
>> introduce overloaded symbols for functions processing CSVstate, making
>> your code
>> more accessible.
>>
>> Also, the following interface:
>>
>> extern fun
>> lex_csv(QNLIN: bool, DELIM: char, cs: llstring): CSVEntries
>>
>> can and probably should be changed into
>>
>> extern
>> fun{}
>> lex_csv(cs: listing): CSVEntries
>>
>> The parameters QNLIN and DELIM can be passed via templates:
>>
>> extern
>> fun{} lex_csv$QNLIN(): char
>> extern
>> fun{} lex_csv$DELIM(): char
>>
>> implement{} lex_csv$QNLIN() = false
>> implement{} lex_csv$DELIM() = ',' // default value
>>
>> Writing function templates (instead of functions) enables you to move
>> your code around very conveniently. You can even move template code
>> into the body of another function.
>>
>> That's all for now. Hope you will like ATS and tell/teach it to your
>> friends.
>>
>> Cheers!
>>
>> On Monday, March 6, 2017 at 4:06:11 PM UTC-5, August Alm wrote:
>>
>> The code now seems to work as inteded!
>>
>> https://github.com/August-Alm/ats_csv_lexer
>>
>> Thank you for all the help. I still don't fully grokk why the function
>> needs to consume each of its arguments--will have to meditate more on
>> that--but at least I know how to write code like this from now on.
>>
>> Den måndag 6 mars 2017 kl. 17:43:36 UTC+1 skrev gmhwxi:
>>
>> Yes, CSVstate needs to be changed as well.
>>
>> However, your code needs very little change. This is like a
>> a 5 minute job to me. I would be happy to give it a try if you say so.
>> But I thought that you might want to get the thrill of fixing the code :)
>>
>> On Monday, March 6, 2017 at 11:30:27 AM UTC-5, August Alm wrote:
>>
>> Hrrm, I had:
>>
>> fun
>> parse_entry
>> ( st: !CSVState >> _
>> , at: (int, int)
>> , acc: !$SBF.stringbuf
>> , cs: llstring
>> ) : stream_vt(CSVEntry)
>>
>> I gather I have to change not just [!$SBF.stringbuf] but also [!CSVState
>> >> _], right? What about if I did
>>
>> fun
>> parse_entry_con
>> ( st: !CSVState >> _
>> , at: (int, int)
>> , acc: !$SBF.stringbuf
>> , cs: llstring
>> ) : stream_vt_con(CSVEntry)
>>
>> and then put
>>
>> parse_entry(...) =
>> $ldelay
>> ( parse_entry_con(...)
>> , ( free(st)
>> ; free(acc)
>> ; free(cs)
>> )
>> )
>>
>> --would that work? Would it be idiomatic and efficient?
>>
>> Thanks, again,
>> August
>>
>> Den måndag 6 mars 2017 kl. 14:30:05 UTC+1 skrev gmhwxi:
>>
>> I forgot to tell you something essential in using stream_vt.
>> The following interface for 'test' cannot work:
>>
>> fun test (acc: !$SBF.stringbuf, cs: llstring): stream_vt(DT) =
>>
>> What you need is
>>
>> fun test (acc: $SBF.stringbuf, cs: llstring): stream_vt(DT) =
>>
>> The 'acc' stringbuf needs to be consumed by 'test'. The implementation
>> of 'test' looks like this:
>>
>> $ldelay
>> (
>> <code for stream construction>
>> ,
>> (freeing(acc); freeing(cs)) // this part is executed when the stream is
>> freed
>> )
>>
>> On Mon, Mar 6, 2017 at 8:19 AM, August Alm <[email protected]> wrote:
>>
>> The points you mention are part of the reason I chose to wrote the csv
>> lexer the way I did. It follows one of the fastests Haskell csv parsers,
>> and I was curious to see how using linear types could optimize performance.
>>
>> Regarding your suggestion on how to make better use of $ldelay in my
>> code: I'm stuck on a compiler error that I can't make sense of. The
>> following pseudo-minimal example throws the same kind of errors:
>>
>> #include "share/atspre_define.hats"
>> #include "share/atspre_staload.hats"
>> staload UN = "prelude/SATS/unsafe.sats"
>> staload SBF = "libats/SATS/stringbuf.sats"
>> staload _(*SBF*) = "libats/DATS/stringbuf.dats"
>>
>> datatype DT = D_T of @{ alpha = char }
>> vtypedef llstring = stream_vt(char)
>>
>> fun
>> test (acc: !$SBF.stringbuf, cs: llstring): stream_vt(DT) =
>> $ldelay
>> ( case !cs of
>> | ~stream_vt_nil() =>
>> if $SBF.stringbuf_get_size(acc) = i2sz(0) then
>> stream_vt_nil()
>> else stream_vt_cons(D_T(@{alpha = 'a'}),
>> stream_vt_make_nil())
>> | ~stream_vt_cons(c, cs1) =>
>> let val crec = D_T(@{alpha = c})
>> in stream_vt_cons(crec, test(acc, cs1))
>> end
>> , ~cs
>> )
>>
>> The compiler can not infer the type I want (which is [stream_vt_con(DT)]
>> for the [stream_vt_nil()] following the first [then] in the function body.
>> The error message says
>>
>> the dynamic expression cannot be assigned the type [S2EVar(5492)].
>> [...] mismatch of sorts in unification:
>> The sort of variable is: S2RTbas(S2RTBASimp(1; t@ype))
>> The sort of solution is: S2RTbas(S2RTBASimp(2; viewtype))
>> [...] mismatch of static terms (tyleq):
>> The actual term is: S2Eapp(S2Ecst(stream_vt_con); S2EVar(5495))
>> The needed term is: S2EVar(5492)
>>
>> (There are further errors of the same form.) Is the culprit that
>> [stream_vt] of a nonlinear datatype requires some special care? The version
>> with [stream_vt_make_nil()] instead of explicit [$ldelay] works so the
>> error ought to be subtle.
>>
>> Best wishes,
>> August
>>
>> Den söndag 5 mars 2017 kl. 23:58:35 UTC+1 skrev gmhwxi:
>>
>> Yes, you definitely got it :)
>>
>> Stream_vt is very memory-frugal.
>>
>> Haskell relies on deforestation (complex complier optimization)
>> to reduce memory usage of lazy evaluation. In ATS, deforestation is
>> not supported. Instead, the programmer needs to recycle memory explicitly.
>>
>> Compared to Haskell, corresponding code using stream_vt in ATS can be
>> much more efficient both time-wise and memory-wise.
>>
>> For instance, the following example (for computing Mersenne primes) can
>> run for days without run-time GC:
>>
>>
>> https://github.com/githwxi/ATS-Postiats/blob/master/doc/EXAMPLE/RosettaCode/Lucas-Lehmer_test2.dats
>>
>> It convincingly attests to the power of linear streams.
>>
>> Cheers!
>>
>>
>> On Sun, Mar 5, 2017 at 5:34 PM, August Alm <[email protected]> wrote:
>>
>> Thanks for the tip! I think I understand. I treated $ldelay much as a
>> data constructor, so that all streams are equally lazy, whereas there are
>> in fact many ways to sequence into thunks. Let me give an example to anchor
>> the discussion. Both the following implementations of a map-template for
>> linear streams typecheck:
>>
>> fun {a, b: t0ype}
>> map_make_cons
>> ( xs: stream_vt(a)
>> , f: a -> b
>> ) : stream_vt(b) =
>> case !xs of
>> | ~stream_vt_nil() => stream_vt_make_nil()
>> | ~stream_vt_cons(x, xs1) =>
>> stream_vt_make_cons(f(x), map_make_cons(xs1, f))
>>
>> fun {a, b: t0ype}
>> map_ldelay
>> ( xs: stream_vt(a)
>> , f: a -> b
>> ) : stream_vt(b) =
>> $ldelay
>> ( case !xs of
>> | ~stream_vt_nil() => stream_vt_nil()
>> | ~stream_vt_cons(x, xs1) =>
>> stream_vt_cons(f(x), map_ldelay(xs1, f))
>> , ~xs
>> )
>>
>> The second is maximally lazy. The first, [map_make_cons] is less lazy
>> because checking the case-conditions is not delayed. My code was like the
>> first example, only much more was going on inside the case expressions. Is
>> that a correct assessment?
>>
>>
>> Den söndag 5 mars 2017 kl. 04:07:42 UTC+1 skrev gmhwxi:
>>
>> BTW, it seems you don't need to do much to fix the issue.
>>
>> Basically, you just do
>>
>> 1) Put the body of parse_entry into $ldelay(...)
>> 2) Change stream_vt_make_cons into stream_vt_cons
>>
>> There may be a few other things but they should all be
>> very minor.
>>
>> On Saturday, March 4, 2017 at 9:47:07 PM UTC-5, gmhwxi wrote:
>>
>> I took a glance at your code.
>>
>> I noticed a very common mistake involving the use of
>> stream (or stream_vt). Basically, the way stream is used
>> in your code is like the way list is used. This causes the
>> stack issue you encountered.
>>
>> Say that you have a function that returns a stream. In nearly
>> all cases, the correct way to implement such a function should
>> use the following style:
>>
>> fun foo(...): stream_vt(...) = $ldelay
>> (
>> ...
>> )
>>
>> The idea is that 'foo' should return in O(1) time. The body of $ldelay
>> is only evaluated with the first element of the returned stream is neede.
>> Sometimes, this is call full laziness. Without full laziness, a stream may
>> behave like a list, defeating the very purpose of using a stream.
>>
>> On Saturday, March 4, 2017 at 7:27:03 PM UTC-5, August Alm wrote:
>>
>> I've spent few hours trying to figure out how to make proper use of npm
>> and gave up--for now. If the project turns into something more serious
>> (i.e., useful to others) then I will have another go at it. For now my
>> naive attempts at making effective use of linear streams can be witnessed
>> at GitHub: https://github.com/August-Alm/ats_csv_lexer Any and all
>> comments on how to improve are appreciated.
>>
>> Best wishes, August.
>>
>> Den fredag 3 mars 2017 kl. 23:57:54 UTC+1 skrev gmhwxi:
>>
>> One possibility is to build a npm package and then publish it.
>>
>> If you go to https://www.npmjs.com/ and seach for 'atscntrb'. You can
>> find
>> plenty packages. You may need to install npm first.
>>
>> If you do build a npm package, I suggest that you choose a name space for
>> yourself. E.g., atscntrb-a?a-..., where ? is the first letter of your
>> middle name.
>>
>> On Fri, Mar 3, 2017 at 5:48 PM, August Alm <[email protected]> wrote:
>>
>> How would I best share larger code portions? I have no concerns about my
>> making my mistakes public, heh.
>>
>> I believe everything is lazy as-is (all data is [stream_vt("sometype")]).
>> And I've tried to write tail-recursive functional code. The algorithm is
>> based on two mutually recursing functions, "fun ... and ..", similar to how
>> you did things in your csv-parser (thanks for pointing out that piece of
>> code). However, I cannot set them up with "fn* .. and .." to enforce a
>> local jump because they call each other in a too intertwined way. Might
>> that be it?
>>
>>
>> Den fredag 3 mars 2017 kl. 23:32:15 UTC+1 skrev gmhwxi:
>>
>> You are welcome!
>>
>> Since I have not seen your code, I could only guess :)
>>
>> Usually, what you described can be fixed by using tail-recursion, or
>> by using lazy-evaluation. The former approach is straightforward. You
>> just need to identify the function or functions that cause the deep stack
>> usage. Then try to rewrite using tail-recursion.
>>
>>
>>
>> On Fri, Mar 3, 2017 at 5:25 PM, August Alm <[email protected]> wrote:
>>
>> Hi!
>> I had indeed made a logical error that caused any stream with "carriage
>> return" followed by "newline" to recurse indefinitely. Thank you for your
>> patience and pedagogical instincts, Professor! There is still some issue
>> though, one that I believe is more subtle. I fixed the logical error and my
>> algorithm now handles all the test cases you suggested. However, when fed
>> an actual CSV-file with a thousand rows and about 300 columns it still
>> segfaults--unless I manually increase the stack space on my computer! I
>> don't know exactly where the critical limit is, but increasing it from 8192
>> kbytes to 65536 certainly did the trick. The whole file parsed without
>> problem, and rather quickly at that. It seems my algorithm makes too much
>> use of stack allocation and that I may have to rethink some of my
>> (would-be) optimization choices.
>> Best wishes,
>> August
>>
>> Den fredag 3 mars 2017 kl. 15:22:00 UTC+1 skrev gmhwxi:
>>
>> Now you may do the following tests:
>>
>> Try:
>>
>> val ins = streamize_string_char("a;b") // should work
>>
>> Try:
>>
>> val ins = streamize_string_char("a;b\n") // may not work
>>
>> Try:
>>
>> val ins = streamize_string_char("a;b\015\012") // should cause crash
>>
>> On Thursday, March 2, 2017 at 9:21:21 PM UTC-5, gmhwxi wrote:
>>
>> When tried, I saw the following 5 chars (ascii) in small.csv:
>>
>> 97
>> 59
>> 98
>> 13
>> 10
>>
>> My testing code:
>>
>> #include"share/atspre_staload.hats"
>> #include"share/HATS/atspre_staload_libats_ML.hats"
>>
>> implement main0 () = {
>> val inp = fileref_open_exn("small.csv", file_mode_r)
>> val ins = streamize_fileref_char(inp)
>> val ins = stream2list_vt(ins)
>> val ins = g0ofg1(list_vt2t(ins))97
>> val ( ) = println! ("length(ins) = ", length(ins))
>> val ( ) = (ins).foreach()(lam c => println!(char2int0(c)))
>> (*
>> val lexed = lex_csv(true, ';', ins)
>> *)
>> val () = fileref_close(inp)
>> (*
>> val h = (lexed.head())
>> val- CSV_Field(r) = h
>> val a = r.csvFieldContent
>> val () = println!(a)
>> *)
>> }
>>
>>
>>
>> On Thu, Mar 2, 2017 at 9:13 PM, August Alm <...> wrote:
>>
>> Just "a;b", or? (Attached.)
>>
>> Den fredag 3 mars 2017 kl. 03:03:08 UTC+1 skrev gmhwxi:
>>
>> I suspect that the file you used contains other characters.
>>
>> What is in "small.csv"?
>>
>> On Thu, Mar 2, 2017 at 8:52 PM, August Alm <...> wrote:
>>
>> The file compiles (I've tried a few compiler options) and "gdb run" yields
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> 0x00007ffff783eea5 in _int_malloc (av=0x7ffff7b6a620 <main_arena>,
>> bytes=16) at malloc.c:3790
>>
>> The frames 0-3 involve allocation functions that are not particular to my
>> file. Frame 4 says:
>>
>> #4 __patsfun_28__28__14 (arg0=<optimized out>, env1=0x605540,
>> env0=10 '\n') at csv_lexer_dats.c:9023
>> 9023 ATSINSmove_con1_new(tmpret63__14, postiats_tysum_7) ;
>>
>> My not-so-educated guess is that this refers to making a cons-cell of a
>> stream.
>>
>> But: How can my function do just fine when manually fed
>>
>> cons('a', cons( ';', sing('b'))): stream_vt(char),
>>
>> but segfault when I use [streamize_fileref_char] to construct the very
>> same stream from the string "a;b" in a file? Where is the room for an
>> infinite recursion in that?
>>
>> Thank you,
>> August
>>
>>
>> Den torsdag 2 mars 2017 kl. 23:04:35 UTC+1 skrev August Alm:
>>
>> Hi!
>>
>> I'm in over my head and tried writing a CSV-parser using linear lazy
>> streams. My code thus far is 600 lines and almost to my own surprise I get
>> it to compile! However, there is something fishy because I get a segfault
>> when applying my program to an actual CSV-file. I've been trying to debug
>> using gdb but the fault eludes me. Since I don't expect anyone to mull
>> through 600 lines of code, I am hoping these code snippets are enough for
>> one of you guys to give me some advice.
>>
>> This code executes just fine:
>>
>> implement main0 () = {
>>
>> val test = stream_vt_make_cons(
>> 'a', stream_vt_make_cons(
>> ';',
>> stream_vt_make_sing('b'))) (* the stream ('a', ';', 'b') *)
>> val lexed = lex_csv(true, ';', test)
>> val h = (lexed.head())
>> val- CSV_Field(r) = h
>> val a = r.csvFieldContent
>> val () = println!(a)
>>
>> }
>>
>> Here [lex_csv] is my 600-line alogrithm. It reads a [stream_vt(char)]
>>
>>
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