https://github.com/FujiiMaika/fscd21.git
Revision 521af9c0dd94b169eb02f41aa19d3e01c558f355 authored by Maika Fujii on 24 June 2021, 05:55:35 UTC, committed by GitHub on 24 June 2021, 05:55:35 UTC
1 parent c230735
Tip revision: 521af9c0dd94b169eb02f41aa19d3e01c558f355 authored by Maika Fujii on 24 June 2021, 05:55:35 UTC
Update README.md
Update README.md
Tip revision: 521af9c
eval.ml
open Syntax
open Value
(* actual calculation *)
(* Definitional interpreter for lambda-calculus with 4 delimited-control operators : eval1 *)
(* initial continuation : v -> t -> m -> v *)
let idc v t m = match t with
TNil ->
begin match m with
MNil -> v
| MCons ((c, t), m) -> c v t m
end
| Trail (h) -> h v TNil m
(* cons : (v -> t -> m -> v) -> t -> t *)
let rec cons h t = match t with
TNil -> Trail (h)
| Trail (h') -> Trail (fun v t' m -> h v (cons h' t') m)
(* apnd : t -> t -> t *)
let apnd t0 t1 = match t0 with
TNil -> t1
| Trail (h) -> cons h t1
(* f1 : e -> string list -> v list -> c -> t -> m -> v *)
let rec f1 e xs vs c t m = match e with
Num (n) -> c (VNum (n)) t m
| Var (x) -> c (List.nth vs (Env.offset x xs)) t m
| Op (e0, op, e1) ->
f1 e0 xs vs (fun v0 t0 m0 ->
f1 e1 xs vs (fun v1 t1 m1 ->
begin match (v0, v1) with
(VNum (n0), VNum (n1)) ->
begin match op with
Plus -> c (VNum (n0 + n1)) t1 m1
| Minus -> c (VNum (n0 - n1)) t1 m1
| Times -> c (VNum (n0 * n1)) t1 m1
| Divide ->
if n1 = 0 then failwith "Division by zero"
else c (VNum (n0 / n1)) t1 m1
end
| _ -> failwith (to_string v0 ^ " or " ^ to_string v1
^ " are not numbers")
end) t0 m0) t m
| Fun (x, e) ->
c (VFun (fun v c' t' m' -> f1 e (x :: xs) (v :: vs) c' t' m')) t m
| App (e0, e1) ->
f1 e0 xs vs (fun v0 t0 m0 ->
f1 e1 xs vs (fun v1 t1 m1 ->
begin match v0 with
VFun (f) -> f v1 c t1 m1
| VContS (c', t') -> c' v1 t' (MCons ((c, t1), m1))
| VContC (c', t') -> c' v1 (apnd t' (cons c t1)) m1
| _ -> failwith (to_string v0
^ " is not a function; it can not be applied.")
end) t0 m0) t m
| Shift (x, e) -> f1 e (x :: xs) (VContS (c, t) :: vs) idc TNil m
| Control (x, e) -> f1 e (x :: xs) (VContC (c, t) :: vs) idc TNil m
| Shift0 (x, e) ->
begin match m with
MCons ((c0, t0), m0) -> f1 e (x :: xs) (VContS (c, t) :: vs) c0 t0 m0
| _ -> failwith "shift0 is used without enclosing reset"
end
| Control0 (x, e) ->
begin match m with
MCons ((c0, t0), m0) -> f1 e (x :: xs) (VContC (c, t) :: vs) c0 t0 m0
| _ -> failwith "control0 is used without enclosing reset"
end
| Reset (e) -> f1 e xs vs idc TNil (MCons ((c, t), m))
(* f : e -> v *)
let f expr = f1 expr [] [] idc TNil MNil
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