module HashableThe difference between(S1:Hashable_sexpable)(S2:Hashable_sexpable):Hashable_sexpablewith type t := Make (S1) (S2).t
Hashable and Hashable_t functors is that the former's
result type doesn't contain type t and the latter does. Therefore, Hashable can't
be used to combine two pairs into 4-tuple. but Hashable_t can. On the other hand
result of Hashable_t cannot be combined with Comparable.
example: module Four_ints = Tuple.Hashable_t (Tuple.Hashable_t (Int)(Int)) (Tuple.Hashable_t (Int)(Int))
If instead we used Hashable compiler would complain that the input to outer functor
doesn't have type t.
On the other hand: module Foo = struct type t = String.t * Int.t include Tuple.Comparable (String.t) (Int) include Tuple.Hashable (String.t) (Int) end
If we used Hashable_t above, compiler would compile that we have two types t
defined.
Unfortunately, it is not possible to define just one functor that could be used in
both cases.
| Parameters: |
|
type
include Hashable.S
include Sexpable.S