Hi all,
On Wed, 28 Sep 2011, Jacques Garrigue wrote:
On 2011/09/28, at 5:22, Walter Cazzola wrote:
I still have one problem: how can I assign to a the type 'a list? by
using «type a= 'a list» I get
Error: Unbound type parameter 'a
Same thing: you need to make explicit the contents of the list.
So this can be type a = int list.
On the other hand if you are trying to refine the signature, you
can also write
type t
type a = t list
keeping t abstract.
thanks for the explanation but I'm still unable to match the 2 types (I
have attached the code again). I get this message:
# module M0 = Continuation(StringConcat);;
Error: Signature mismatch:
Modules do not match:
sig
type t = StringConcat.t
type a = t list
and b = t
and c = t list
val op : 'a -> 'a list -> 'a list
val init : 'a list
end
is not included in
OpVarADT.OpVarADT
Values do not match:
val op : 'a -> 'a list -> 'a list
is not included in
val op : a -> b -> c
I have also tried to set the abstract type t to string butwithout any
luck.
# module M0 = Continuation(StringConcat with StringConcat.t = string) ;;
Error: Syntax error
I feel myself quite dumb but I can't figure out how to fix it.
Walter
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module Continuation (OP : OpVarADT.OpVarADT) =
struct
let arg x = fun y continuation -> continuation (OP.op x y) ;;
let stop x = x;;
let f g = g OP.init;;
end
module type OpVarADT =
sig
type a and b and c
val op: a -> b -> c
val init : c
end
module StringConcat = struct
type t
type a=t list and b=t and c=t list
let op = fun x y -> y @ [x] ;;
let init = [] ;;
end
