package core_kernel

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package core_kernel
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The difference between 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) (Int) include Tuple.Hashable (String) (Int) end

If we used Hashable_t above, the compiler would complain 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

Signature

include sig ... end
include Hashable.S with type t := Tuple.Make(S1)(S2).t
include Hashable.Common with type t := Tuple.Make(S1)(S2).t
include sig ... end
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