heptagon/compiler/global/linearity.ml
2011-05-25 09:12:13 +02:00

67 lines
1.6 KiB
OCaml

open Format
open Names
open Misc
type linearity_var = name
type linearity =
| Ltop
| Lat of linearity_var
| Lvar of linearity_var (*a linearity var, used in functions sig *)
| Ltuple of linearity list
module LinearitySet = Set.Make(struct
type t = linearity
let compare = compare
end)
(** Returns a linearity object from a linearity list. *)
let prod = function
| [l] -> l
| l -> Ltuple l
let linearity_list_of_linearity = function
| Ltuple l -> l
| l -> [l]
let rec lin_skeleton lin = function
| Types.Tprod l -> Ltuple (List.map (lin_skeleton lin) l)
| _ -> lin
(** Same as Misc.split_last but on a linearity. *)
let split_last_lin = function
| Ltuple l ->
let l, acc = split_last l in
Ltuple l, acc
| l ->
Ltuple [], l
let rec is_not_linear = function
| Ltop -> true
| Ltuple l -> List.for_all is_not_linear l
| _ -> false
exception UnifyFailed
(** Unifies lin with expected_lin and returns the result
of the unification. Applies subtyping and instantiate linearity vars. *)
let rec unify_lin expected_lin lin =
match expected_lin,lin with
| Ltop, Lat _ -> Ltop
| Ltop, Lvar _ -> Ltop
| Lat r1, Lat r2 when r1 = r2 -> Lat r1
| Ltop, Ltop -> Ltop
| Ltuple l1, Ltuple l2 -> Ltuple (List.map2 unify_lin l1 l2)
| Lvar _, Lat r -> Lat r
| Lat r, Lvar _ -> Lat r
| _, _ -> raise UnifyFailed
let rec lin_to_string = function
| Ltop -> "at T"
| Lat r -> "at "^r
| Lvar r -> "at _"^r
| Ltuple l_list -> String.concat ", " (List.map lin_to_string l_list)
let print_linearity ff l =
fprintf ff " %s" (lin_to_string l)