Merging stream_vt

[aditya siram]

I trying to understand the stream_vt datatype by writing a function that merges two streams in a stream of tuples but not having much luck, the following:

fun merge
  {a: t@ype}
  {b: t@ype}
  (
    s1: stream_vt a,
    s2: stream_vt b
  ) : stream_vt(@(a,b)) =
  let
    val _s1 = !s1
    val _s2 = !s2
  in
    $ldelay
     (
      case+ (_s1,_s2) of
      | (~stream_vt_cons(_s1, _s1s),
         ~stream_vt_cons(_s2, _s2s)) =>
             stream_vt_cons((_s1,_s2), merge(_s1s,_s2s))
      | (_,_) => stream_vt_nil()
     )
  end

gives me the errors:

...: 465(line=27, offs=9) -- 590(line=29, offs=57): error(3): the dynamic variable [_s2$4720(-1)] is consumed but it should be retained with the type [S2Eapp(S2Ecst(stream_vt_con); S2Evar(b(8451)))] instead.
...: 465(line=27, offs=9) -- 590(line=29, offs=57): error(3): the dynamic variable [_s1$4719(-1)] is consumed but it should be retained with the type [S2Eapp(S2Ecst(stream_vt_con); S2Evar(a(8450)))] instead.
...: 368(line=20, offs=3) -- 636(line=32, offs=6): error(3): the linear dynamic variable [_s1$4719(-1)] needs to be consumed but it is preserved with the type [S2Eapp(S2Ecst(stream_vt_con); S2Evar(a(8450)))] instead.
...: 368(line=20, offs=3) -- 636(line=32, offs=6): error(3): the linear dynamic variable [_s2$4720(-1)] needs to be consumed but it is preserved with the type [S2Eapp(S2Ecst(stream_vt_con); S2Evar(b(8451)))] instead.
patsopt(TRANS3): there are [4] errors in total.
exit(ATS): uncaught exception: _2home_2deech_2ATS_2triples_2dats_2ATS_2ATS2_2src_2pats_error_2esats__FatalErrorExn(1025)

Any help is appreciated.

Thanks!

[Artyom Shalkhakov]

Hello Aditya!

I've modified this a bit by inserting freeing:

fun merge
  {a: t@ype}
  {b: t@ype}
  (
    s1: stream_vt a,
    s2: stream_vt b
  ) : stream_vt(@(a,b)) =
  let
    val _s1 = !s1
    val _s2 = !s2
  in
    $ldelay
     (

      (
      case+ (_s1,_s2) of
      | (~stream_vt_cons(_s1e, _s1s),
         ~stream_vt_cons(_s2e, _s2s)) =>
             stream_vt_cons(@(_s1e,_s2e), merge(_s1s,_s2s))
      | (~stream_vt_nil (), _) => (stream_vt_con_free(_s2); stream_vt_nil())
      | (_, ~stream_vt_nil ()) => (stream_vt_con_free(_s1); stream_vt_nil())
      )
     , (stream_vt_con_free(_s1); stream_vt_con_free(_s2))
     )
  end

This type-checks (but I have not run it).

$ldelay requires us to supply as its second argument an expression that will free up all resources that are used in its first argument.

ср, 2 янв. 2019 г. в 08:10, aditya siram <aditya...@gmail.com>:

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Artyom Shalkhakov

[aditya siram]

Awesome. That does typecheck but when I try to build it with:

"$PATSHOME/bin/patscc" -O3 -flto -s -D_GNU_SOURCE -DATS_MEMALLOC_LIBC -I${PATSHOME}/contrib -O3 -o triples triples.dats -latslib

I get:

/home/deech/ATS/test/ATS/ATS2/ccomp/runtime/pats_ccomp_instrset.h:276:35: error: assignment to expression with array type
 #define ATSINSmove(tmp, val) (tmp = val)
                                   ^
triples_dats.c:1062:1: note: in expansion of macro ‘ATSINSmove’
 ATSINSmove(tmp19, ATSSELcon(env0, postiats_tysum_3, atslab__0)) ;
 ^~~~~~~~~~
/home/deech/ATS/test/ATS/ATS2/ccomp/runtime/pats_ccomp_instrset.h:276:35: error: assignment to expression with array type
 #define ATSINSmove(tmp, val) (tmp = val)
                                   ^
triples_dats.c:1070:1: note: in expansion of macro ‘ATSINSmove’
 ATSINSmove(tmp21, ATSSELcon(env1, postiats_tysum_4, atslab__0)) ;
 ^~~~~~~~~~
/home/deech/ATS/test/ATS/ATS2/ccomp/runtime/pats_ccomp_instrset.h:327:65: error: assignment to expression with array type
 #define ATSINSstore_fltrec_ofs(tmp, tyrec, lab, val) ((tmp).lab = val)
                                                                 ^
triples_dats.c:1093:1: note: in expansion of macro ‘ATSINSstore_fltrec_ofs’
 ATSINSstore_fltrec_ofs(tmp23, postiats_tyrec_2, atslab__0, tmp19) ;
 ^~~~~~~~~~~~~~~~~~~~~~
/home/deech/ATS/test/ATS/ATS2/ccomp/runtime/pats_ccomp_instrset.h:327:65: error: assignment to expression with array type
 #define ATSINSstore_fltrec_ofs(tmp, tyrec, lab, val) ((tmp).lab = val)
                                                                 ^
triples_dats.c:1094:1: note: in expansion of macro ‘ATSINSstore_fltrec_ofs’
 ATSINSstore_fltrec_ofs(tmp23, postiats_tyrec_2, atslab__1, tmp21) ;
 ^~~~~~~~~~~~~~~~~~~~~~

[Artyom Shalkhakov]

ср, 2 янв. 2019 г. в 09:41, aditya siram <aditya...@gmail.com>:

Awesome. That does typecheck but when I try to build it with:

"$PATSHOME/bin/patscc" -O3 -flto -s -D_GNU_SOURCE -DATS_MEMALLOC_LIBC -I${PATSHOME}/contrib -O3 -o triples triples.dats -latslib

I don't have a compiler with me here but it seems like the function should be made into a template (i.e. the type parameters should be put prior to the function's name in the declaration).

This typechecks and the online compiler will accept it:

fun test (): void = {
  val xs = stream_vt_make_cons ((g0ofg1)1, stream_vt_make_cons ((g0ofg1)2, stream_vt_make_nil{int} ()))
 
  val ys = stream_vt_make_cons ((g0ofg1)"x", stream_vt_make_cons ((g0ofg1)"y", stream_vt_make_nil{string} ()))

  val zs = merge<int><string> (xs, ys)
 
  val l = stream2list_vt (zs)
  val () = println!(l) // should print something like: 1,x; 2,y

  val () = list_vt_free(l)
}

Unfortunately I can't run it (the glot.io-provided compiler doesn't support stream_vt_make_* functions).

To view this discussion on the web visit https://groups.google.com/d/msgid/ats-lang-users/ee6d25b3-4790-4d5e-b1d0-e61d66f20a7a%40googlegroups.com.

--

Cheers,
Artyom Shalkhakov

[Richard]

Yes, this compiles and runs as expected. Although, I am not sure that I have ever used 'stream_vt_con_free'. A slightly different way to do the same without using stream_vt_con_free,

#include "share/atspre_staload.hats"

extern fun {a:t@ype}{b:t@ype}
  merge : (stream_vt a, stream_vt b) -> stream_vt(@(a,b))

implement{a}{b} merge (xs, ys) = let
fun
auxmain (xs: stream_vt a, ys: stream_vt b) : stream_vt(@(a,b)) = $ldelay
(
(
  case+ !xs of
  | ~stream_vt_nil() => (~ys; stream_vt_nil())
  | ~stream_vt_cons(x, xs) =>
    case+ !ys of
    | ~stream_vt_nil() => (~xs; stream_vt_nil())
    | ~stream_vt_cons(y, ys) =>
      stream_vt_cons(@(x, y), auxmain(xs, ys))
) ,
(
  ~xs; ~ys
)
)
in
  auxmain(xs, ys)
end

To test,

implement main0() =
{
  val xs = streamize_list_vt_elt($list_vt{int}(1, 2))
  val ys = streamize_list_vt_elt($list_vt{string}("x", "y"))

[Artyom Shalkhakov]

Hi Richard,

ср, 2 янв. 2019 г. в 17:35, Richard <qpo...@gmail.com>:

Yes, this compiles and runs as expected. Although, I am not sure that I have ever used 'stream_vt_con_free'. A slightly different way to do the same without using stream_vt_con_free,

#include "share/atspre_staload.hats"

extern fun {a:t@ype}{b:t@ype}
  merge : (stream_vt a, stream_vt b) -> stream_vt(@(a,b))

implement{a}{b} merge (xs, ys) = let
fun
auxmain (xs: stream_vt a, ys: stream_vt b) : stream_vt(@(a,b)) = $ldelay
(
(
  case+ !xs of
  | ~stream_vt_nil() => (~ys; stream_vt_nil())
  | ~stream_vt_cons(x, xs) =>
    case+ !ys of
    | ~stream_vt_nil() => (~xs; stream_vt_nil())
    | ~stream_vt_cons(y, ys) =>
      stream_vt_cons(@(x, y), auxmain(xs, ys))
) ,
(
  ~xs; ~ys
)
)
in
  auxmain(xs, ys)
end

My guess is that the prefix ~ operator is the "stream_vt_free". :-) I did not know it has an operator attached to it, thanks for pointing it out!

 

To view this discussion on the web visit https://groups.google.com/d/msgid/ats-lang-users/5b227e90-3395-44ab-aee7-b648408ae4a2%40googlegroups.com.

--

Cheers,
Artyom Shalkhakov