From 995d95df41b6cf2881aa2b4e21c4fc01840da6e1 Mon Sep 17 00:00:00 2001
From: Hyeonung Baek <wiserlix@gmail.com>
Date: Mon, 7 Feb 2022 01:09:57 +0900
Subject: [PATCH] Seperate Ast and value (which should be in Eval)

---
 ast.ml    | 38 ++++++++++++++++++++++++--------------
 eval.ml   |  6 +++++-
 main.ml   |  4 ++--
 parser.ml | 10 +++++-----
 4 files changed, 36 insertions(+), 22 deletions(-)

diff --git a/ast.ml b/ast.ml
index 13a1a38..961a9c1 100644
--- a/ast.ml
+++ b/ast.ml
@@ -20,7 +20,11 @@ end
 
 (* simple, untyped AST. *)
 type t =
-  | Value of value
+  | Nint of int
+  | Nfloat of float
+  | Nstring of string
+  | Nfunction of string list * t
+  | Nexternal of string
   | Var of string
   | Let of string * t
   | Unary of operator * t
@@ -31,14 +35,6 @@ type t =
   | Set_binop_aso of operator * string
   | Get_binop_aso of operator
 
-and value =
-  | Int of int
-  | Float of float
-  | String of string
-  | Function of string list * t
-  | External of string
-  | Nop (* return of system operations (will be deprecated) *)
-
 and operator =
   | Add | Sub | Mul | Div (* arithmetics *)
   | Mod (* modular operation *)
@@ -48,7 +44,15 @@ and operator =
 exception Invalid_type of Type.t
 
 module Value = struct
-  type t = value
+  type expr = t
+
+  type t =
+  | Int of int
+  | Float of float
+  | String of string
+  | Function of string list * expr
+  | External of string
+  | Nop (* return of system operations (will be deprecated) *)
 
   let to_string = function
     | Int n -> string_of_int n
@@ -88,6 +92,8 @@ module Operator = struct
     | Exp -> "^"
     | Negate -> "-"
 
+  open Value
+
   let negate = function
     | Int n -> Int ~-n
     | Float n -> Float ~-.n
@@ -131,8 +137,6 @@ module Operator = struct
     |> List.assoc_opt typ
 end
 
-let value v = Value v
-
 let unary op t =
   Unary (op, t)
 
@@ -142,9 +146,15 @@ let binop left op right =
 (* print ast LISP style. *)
 let print ast =
   let pr = Printf.printf in
-  let pv v = pr "%s" @@ Value.to_string v in
   let rec aux = function
-    | Value n -> pv n
+    | Nint n -> pr "%d" n
+    | Nfloat n -> pr "%f" n
+    | Nstring s -> pr "\"%s\"" s
+    | Nfunction (args, e) ->
+      pr "lambda (%s" @@ List.hd args;
+      List.iter (pr " %s") @@ List.tl args;
+      pr ") ("; aux e; pr")"
+    | Nexternal e -> pr "(extern %s)" e
     | Var v -> pr "%s" v
     | Let (v, e) ->
       pr "(let %s " v; aux e; pr ")"
diff --git a/eval.ml b/eval.ml
index 117a2dd..52cc6a5 100644
--- a/eval.ml
+++ b/eval.ml
@@ -70,7 +70,11 @@ let ex_apply f args =
 
 let rec eval env ast =
   let rec aux = function
-    | Value v -> v
+    | Nint n -> Int n
+    | Nfloat n -> Float n
+    | Nstring s -> String s
+    | Nfunction (args, e) -> Function (args, e)
+    | Nexternal f -> External f
     | Var v -> begin match Env.get_opt env v with
         | None -> raise @@ No_such_variable v
         | Some v -> v
diff --git a/main.ml b/main.ml
index 7d2c860..4ff2848 100644
--- a/main.ml
+++ b/main.ml
@@ -24,7 +24,7 @@ let stdlib = [
   "deg"; "rad";
 ]
   |> List.to_seq
-  |> Seq.map (fun v -> v, Ast.External v)
+  |> Seq.map (fun v -> v, Ast.Value.External v)
 
 let g =
   let g = Env.init_global () in
@@ -51,7 +51,7 @@ let rep env : unit =
 exception Reset_line (* used to indicate ^C is pressed *)
 
 let init_repl () =
-  Env.set g "ans" (Ast.Int 0);
+  Env.set g "ans" (Ast.Value.Int 0);
   (* treat Ctrl-C as to reset line *)
   let reset_line _ = raise Reset_line in
   Sys.(set_signal sigint (Signal_handle reset_line))
diff --git a/parser.ml b/parser.ml
index 7a012bc..2362462 100644
--- a/parser.ml
+++ b/parser.ml
@@ -192,7 +192,7 @@ and lambda seq =
   let vars, seq = more any_ident seq in
   let _, seq = token Right_arrow seq in
   let e, seq = expr min_int seq in
-  Value (Function (v0::vars, e)), seq
+  Nfunction (v0::vars, e), seq
 
 (* apply := value [value]+ *)
 and apply seq =
@@ -205,7 +205,7 @@ and apply seq =
 and extern_value seq =
   let _, seq = ident "external" seq in
   let id, seq = any_ident seq in
-  Value (External id), seq
+  Nexternal id, seq
 
 (* unary := - value *)
 and unary seq =
@@ -226,9 +226,9 @@ and value seq =
   | Seq.Nil -> raise End_of_tokens
   | Seq.Cons (x, seq) -> begin match x with
       | Token.Ident id -> Var id, seq
-      | Int x -> Value (Int x), seq
-      | Float x -> Value (Float x), seq
-      | String x -> Value (String x), seq
+      | Int x -> Nint x, seq
+      | Float x -> Nfloat x, seq
+      | String x -> Nstring x, seq
       | LParen ->
         let e, seq = expr min_int seq in
         let _, seq = token RParen seq in