Source file record_builder.ml
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open Base
module Hlist = Hlist
include Record_builder_intf
module Make_internal(F : Partial_applicative_S2) = struct
(** An internal type which is a special case of [F] constructing an [Hlist]. *)
module Hlist_F = struct
type ('a, 'e) t =
| Nil : (Hlist.nil, 'e) t
| Cons : (('x, 'xs) Hlist.cons Hlist.t, 'e) F.t -> (('x, 'xs) Hlist.cons, 'e) t
let cons (type a b)
(left : (a, _) F.t) (right : (b, _) t)
: ((a, b) Hlist.cons, _) t
= match right with
| Nil -> Cons (F.map left ~f:(fun x -> Hlist.cons x Hlist.empty))
| Cons right -> Cons (F.both left right)
;;
let unpack ((Cons x) : ((_, _) Hlist.cons, _) t) = x
end
module Make_creator_types = struct
type ('out, 'all_fields, 'extra) accum =
(('out, 'extra) Hlist_F.t -> ('all_fields, 'extra) Hlist_F.t)
* ('all_fields, 'out) Hlist.Suffix_index.t
type ('field, 'head, 'tail, 'all_fields, 'extra) fold_step =
('head, 'all_fields, 'extra) accum
-> ('all_fields -> 'field) * ('tail, 'all_fields, 'extra) accum
type ('field, 'tail, 'all_fields, 'extra) handle_one_field =
('field, ('field, 'tail) Hlist.cons, 'tail, 'all_fields Hlist.nonempty, 'extra) fold_step
type ('record, 'all_fields, 'extra) handle_all_fields =
('record, 'all_fields Hlist.nonempty, Hlist.nil, 'all_fields Hlist.nonempty, 'extra) fold_step
end
let field applicative _field (build_hlist, suffix) =
let build_hlist tail =
build_hlist (Hlist_F.cons applicative tail)
and get_field =
let index = Hlist.Element_index.(within ~suffix first_element) in
fun hlist -> Hlist.nth hlist index
and suffix = Hlist.Suffix_index.tail_of suffix
in
get_field, (build_hlist, suffix)
;;
let build_for_record folding =
let from_values, (build_up, _) =
folding (Fn.id, Hlist.Suffix_index.whole_list)
in
let built = Hlist_F.(unpack (build_up Nil)) in
F.map built ~f:from_values
;;
end
module Make(F : Partial_applicative_S) = struct
type 'a applicative = 'a F.t
include Make_internal(struct
type ('a, 'e) t = 'a applicative
let map = F.map
let both = F.both
end)
end
module Make_2(F : Partial_applicative_S2) = struct
type ('a, 'e) applicative = ('a, 'e) F.t
include Make_internal(F)
end