List.AssocInterpret a list of (key, value) pairs as a map in which only the first occurrence of a key affects the semantics, i.e.:
List.Assoc.xxx alist ...args... is always the same as (or at least sort of isomorphic to):
Map.xxx (alist |> Map.of_alist_multi |> Map.map ~f:List.hd) ...args... include Sexpable.S2 with type ('a, 'b) t := ('a, 'b) tval t_of_sexp : (Sexplib0.Sexp.t -> 'a) -> (Sexplib0.Sexp.t -> 'b) -> Sexplib0.Sexp.t -> ('a, 'b) tval sexp_of_t : ('a -> Sexplib0.Sexp.t) -> ('b -> Sexplib0.Sexp.t) -> ('a, 'b) t -> Sexplib0.Sexp.tval find : ('a, 'b) t -> equal:('a -> 'a -> bool) -> 'a -> 'b optionval find_exn : ('a, 'b) t -> equal:('a -> 'a -> bool) -> 'a -> 'bval mem : ('a, 'b) t -> equal:('a -> 'a -> bool) -> 'a -> bool