diff options
Diffstat (limited to 'discocaml/eval.ml')
| -rw-r--r-- | discocaml/eval.ml | 38 |
1 files changed, 31 insertions, 7 deletions
diff --git a/discocaml/eval.ml b/discocaml/eval.ml index aa90d41..5e2cae4 100644 --- a/discocaml/eval.ml +++ b/discocaml/eval.ml @@ -5,11 +5,9 @@ exception FoundRedex of expr index let check_redex (ast : expr ast) (i : expr index) : unit = match get_subexpr ast i with | App (f, _) -> ( - match get_subexpr ast f with - | Lam (_, _) -> raise (FoundRedex i) - | _ -> ()) + match get_subexpr ast f with Lam _ -> raise (FoundRedex i) | _ -> ()) | Int _ -> () - | Lam (_, _) -> () + | Lam _ -> () | Prim (Add, (l, r)) | Prim (Sub, (l, r)) | Prim (Mul, (l, r)) -> ( match (get_subexpr ast l, get_subexpr ast r) with | Int _, Int _ -> raise (FoundRedex i) @@ -23,7 +21,7 @@ let find_redex_cbv_in (ast : expr ast) : expr index -> unit = loop f; loop x | Int _ -> () - | Lam (_, _) -> () + | Lam _ -> () | Prim (Add, (l, r)) | Prim (Sub, (l, r)) | Prim (Mul, (l, r)) -> loop l; loop r @@ -40,7 +38,7 @@ let find_redex_cbn_in (ast : expr ast) : expr index -> unit = loop f; loop x | Int _ -> () - | Lam (_, _) -> () + | Lam _ -> () | Prim (Add, (l, r)) | Prim (Sub, (l, r)) | Prim (Mul, (l, r)) -> loop l; loop r @@ -62,13 +60,39 @@ let find_redex_cbn (ast : expr ast) : expr index option = exception NotARedex of expr ast +let subst (ast : expr ast) (from : string) (to_ : expr index) : + expr index -> expr index = + let rec loop (i : expr index) : expr index = + let add (expr : expr) : expr index = + if get_subexpr ast i = expr then i + else + let index = Arraylist.length ast.subexprs in + Arraylist.push ast.subexprs expr; + { index } + in + match get_subexpr ast i with + | App (f, x) -> + let f' = loop f and x' = loop x in + add (App (f', x')) + | Int _ -> i + | Lam (x, b) -> if String.equal from x then i else add (Lam (x, loop b)) + | Prim (Add, (l, r)) -> add (Prim (Add, (loop l, loop r))) + | Prim (Sub, (l, r)) -> add (Prim (Sub, (loop l, loop r))) + | Prim (Mul, (l, r)) -> add (Prim (Mul, (loop l, loop r))) + | Var x -> if String.equal from x then to_ else i + in + loop + let reduce (ast : expr ast) (i : expr index) : expr ast = let fail () = raise (NotARedex { ast with root = i }) in let ast = copy ast in let must_int j = match get_subexpr ast j with Int n -> n | _ -> fail () in Arraylist.set ast.subexprs i.index (match get_subexpr ast i with - | App (_f, _x) -> failwith "TODO" + | App (f, x) -> ( + match get_subexpr ast f with + | Lam (x', b) -> get_subexpr ast (subst ast x' x b) + | _ -> fail ()) | Prim (Add, (l, r)) -> Int (must_int l + must_int r) | Prim (Sub, (l, r)) -> Int (must_int l - must_int r) | Prim (Mul, (l, r)) -> Int (must_int l * must_int r) |