I believe you were just missing the [@@] prefix for identifiers, to
disable implicit argument resolution in particular cases.
structure Foldable : sig
class foldable :: (Type -> Type) -> Type
val mkFoldable : t ::: (Type -> Type) -> (a ::: Type -> b ::: Type ->
((a -> b -> b) -> b -> t a -> b)) -> foldable t
val foldr : t ::: (Type -> Type) -> a ::: Type -> b ::: Type ->
foldable t -> (a -> b -> b) -> b -> t a -> b
end = struct
type foldable t = a ::: Type -> b ::: Type -> (a -> b -> b) -> b ->
t a -> b
fun mkFoldable [t](f: a ::: Type -> b ::: Type -> (a -> b -> b) ->
b -> t a -> b) = @@f
fun foldr [t][a][b] (f: foldable t): (a -> b -> b) -> b ->
t a -> b = f
end
open Foldable
val foldable_list : foldable list = mkFoldable @@List.foldr
On 01/23/2015 03:19 AM, Gabriel Riba wrote:
I have another question about free type variables of class methods. I can
make them work by bringing them to class parameters.
(* Foldable *)
structure Foldable : sig
class foldable :: (Type -> Type) -> Type -> Type -> Type
val mkFoldable : t ::: (Type -> Type) -> a ::: Type -> b ::: Type ->
((a -> b -> b) -> b -> t a -> b) -> foldable t a b
val foldr : t ::: (Type -> Type) -> a ::: Type -> b ::: Type ->
foldable t a b -> (a -> b -> b) -> b -> t a -> b
end = struct
type foldable t = fn a b => (a -> b -> b) -> b -> t a -> b
fun mkFoldable [t][a][b](f: (a -> b -> b) -> b -> t a -> b) = f
val foldr [t][a][b] (f: foldable t a b): (a -> b -> b) -> b ->
t a -> b = f
end
open Foldable
val foldable_list [a][b]: foldable list a b = mkFoldable List.foldr
(* --- *)
Is there a way to define the free type variables of methods existentially or
should I stick to the previous design?
(* --- *)
type foldable t = a :::Type -> b:::Type -> (a -> b -> b) -> b -> t a -> b
(* --- *)
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