Module type Stdune.MonoidSource

Sourcetype t
Sourceval empty : t

Must be the identity of combine:

  • combine empty t = t
  • combine t empty = t
Sourceval combine : t -> t -> t

Must be associative:

  • combine a (combine b c) = combine (combine a b) c
Sourcemodule O : sig ... end
Sourceval reduce : t list -> t
Sourceval map_reduce : f:('a -> t) -> 'a list -> t