Fabrice Marchant a écrit :
> Here is a counter functor : *)
> [...]
> (* before Counters, that would be modified this way :
> *)
> module Counters ( X : Map.OrderedType ) :
> sig
> module XMap :
> sig
> type 'a t = 'a Map.Make(X).t
> val empty : 'a t
> val add : X.t -> 'a -> 'a t -> 'a t
> val find : X.t -> 'a t -> 'a
> val fold : (X.t -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
> val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
> end
> type t = int XMap.t
> val equal : t -> t -> bool
> val zeroes : t
> val incr : t -> X.t -> t
> end
> =
> struct
> module XMap = MapPlus ( Map.Make( X ) )
>
> type t = int XMap.t
>
> let equal = XMap.equal ( = )
>
> let zeroes = XMap.empty
>
> let incr map e =
> (XMap.add e
> (try succ (XMap.find e map)
> with Not_found -> 1)) map
> end
>
> (* unfortunately this doesn't work : how to access 'to_list' function through
> the Counters module ? With StringCounters.XMap.to_list ?
> I'm confused. Should the Counters signature be modified ?
You need
- either to export to_list in signature of XMap above as
val to_list : 'a t -> (X.t * 'a) list
and then you'll be able to write StringCounters.XMap.to_list in your
example
- or to re-export it in module Counters, as
let to_list = XMap.to_list
and to declare it in signature of module Counters, as
val to_list : t -> (X.t * int) list
and then to use it as StringCounters.to_list in your example.
Hope this helps,
--
Jean-Christophe
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