Templates and closures

[chotu s]

Hello ,

Any idea why test2 function does not work in this code :

#include "share/atspre_define.hats"
#include "share/atspre_staload.hats"
staload UN = "prelude/SATS/unsafe.sats"


extern
fun{a:t@ype}
test (f : &(&int) -<clo1> void ) : void

implement{a}
test (f) = {}

extern
fun{a:t@ype}
test2(f : &(&a) -<clo1> void ) : void

implement{a}
test2 (f) = {}

implement main0 () = {
  var f = lam@ (x : &int) : void => {} 
  val () = test<int> (f)
  val () = test2<int> (f)
}

[gmhwxi]

This involves a very subtle point in typechecking.

The code should work if you make the following change:

extern
fun{a:t@ype}
test2(f : &(&(INV(a)) -<clo1> void ) : void

[chotu s]

Thanks , it now works properly. I'll look at INV later.

In array.sats (development version , 0,0,07) , the array_foreach_clo is define like this :

fun{a:vt0p}
array_foreach_clo
  {n:int}{fe:eff}
(
  A: &(@[INV(a)][n])
, asz: size_t n
, f: &(&a) -<clo,fe> void
) :<fe> void // end of [array_foreach_clo]

Should it not be defined like this :

extern
fun{a:vt0p}
array_foreach_clo
  {n:int}{fe:eff}
(
  A: &(@[INV(a)][n])
, asz: size_t n
, f: &(&(INV(a))) -<clo,fe> void
) :<fe> void // end of [array_foreach_clo]

only difference is in type of f .

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[chotu s]

Can I also make closure function name visible inside a nested function i.e

implement{a}

fun (A,B,f) = {

 implement somefun<a> () = //make f visible here
 .....
}

 

[gmhwxi]

I took a look. It should be:

fun{a:vt0p}
array_foreach_clo
  {n:int}{fe:eff}
(

  A: &(@[INV(a)][n]) >> @[a][n]
, asz: size_t (n), f: &(&a >> _) -<clo,fe> void

) :<fe> void // end of [array_foreach_clo]

I have to say that this function and similar ones are kept mainly for the purpose of
indicating how awkward the situation was in ATS1.

I suggest that you use array_foreach and array_foreach_env.

[gmhwxi]

Yes, you can.