I want to create abstract types such that

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1

I want to create two abstract type say T1,T2 . I also want some
relationship between T1 and T2 say I want that T2 is a subtype of T1 i.e T2
<= T1

Finally I want a function of one argument that takes a not only of type T1
, but also all subtypes of T1 which includes T2.

Is it possible to create such type hierarchy in ATS ?

I know I can use t@ype+ , but I’ll like to see full example if possible.

Thanks.

2

My prev post was lost , so apology if you get double posting

So I did take a quick look at gtk sat files , and managed to use classdec
in a program successfully.

A code using classdec that I tried(which compiles successfully) :

#include “share/atspre_define.hats”
#include “share/atspre_staload.hats”

classdec CAT1
classdec CAT2 : CAT1
classdec CAT3

abstype AT1 ( c : cls) = ptr

stadef C1 = CAT1
typedef C1 = [c : cls | c <= C1] AT1 (c)

stadef C2 = CAT2
typedef C2 = [c : cls | c <= C2] AT1 (c)

extern
fun make_c1 () : AT1 (CAT1) = “mac#”

extern
fun make_c2 () : AT1 (CAT2) = “mac#” //C2

(* extern )
( fun take_c1 {c:cls | c <= CAT1} (pc : AT1 (c) ) : void )
( extern )
( fun take_c2 {c:cls | c <= CAT2} (pc : AT1 (c) ) : void *)

extern
fun take_c1 (pc : C1 ) : void = “mac#”
extern
fun take_c2 (pc : C2 ) : void = “mac#”

implement main0 () = {
val c1 = make_c1 ()
val c2 = make_c2 ()
val () = take_c1 (c1)
val () = take_c1 (c2)
val () = take_c2 (c2)
(* val () = take_c2 (c1) *) //this should not work if we uncomment it
}

I also used classes in datatype which was interesting . I’ll try to
program little more of it to understand it better

ThanksOn Sat, Mar 1, 2014 at 10:28 PM, gmhwxi gmh...@gmail.com wrote:

Yes, you can.

This sounds like a class hierarchy.

Take a look at

ATSCNTRB/contrib/GTK for examples using classdec.

On Saturday, March 1, 2014 2:34:02 AM UTC-5, chotu s wrote:

I want to create two abstract type say T1,T2 . I also want some
relationship between T1 and T2 say I want that T2 is a subtype of T1 i.e T2
<= T1

Finally I want a function of one argument that takes a not only of type
T1 , but also all subtypes of T1 which includes T2.

Is it possible to create such type hierarchy in ATS ?

I know I can use t@ype+ , but I’ll like to see full example if possible.

Thanks.

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3

Yes, you can.

This sounds like a class hierarchy.

Take a look at

ATSCNTRB/contrib/GTK for examples using classdec.On Saturday, March 1, 2014 2:34:02 AM UTC-5, chotu s wrote:

I want to create two abstract type say T1,T2 . I also want some
relationship between T1 and T2 say I want that T2 is a subtype of T1 i.e T2
<= T1

Finally I want a function of one argument that takes a not only of type T1
, but also all subtypes of T1 which includes T2.

Is it possible to create such type hierarchy in ATS ?

I know I can use t@ype+ , but I’ll like to see full example if possible.

Thanks.

4

Good for you!

This feature (classdec) is primarily for building API for an external
package (e.g., GTK)
written in a OOP style. ATS itself does have direct support for OOP.On Saturday, March 1, 2014 2:34:02 AM UTC-5, chotu s wrote:

I want to create two abstract type say T1,T2 . I also want some
relationship between T1 and T2 say I want that T2 is a subtype of T1 i.e T2
<= T1

Finally I want a function of one argument that takes a not only of type T1
, but also all subtypes of T1 which includes T2.

Is it possible to create such type hierarchy in ATS ?

I know I can use t@ype+ , but I’ll like to see full example if possible.

Thanks.