Add merlin to the devshell, because I use emacs

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -1,2 +1,4 @@
 _build
 *~
+.direnv
+result

bin/dune

@@ -1,6 +1,5 @@
 (executable
- (name main)
- (public_name main)
- (libraries str lisp unix))
-(include_subdirs unqualified)
-
+ (name inter)
+ (public_name ollisp-inter)
+ (libraries str unix interpreter)
+ (package ollisp))

bin/inter.ml

@@ -1,11 +1,10 @@
-open Lisp.Ast;;
+open Interpreter.Ast;;
 open Printf;;
-open Lisp;;
+open Interpreter;;
 open Env;;
 open Eval;;
-open Read;;
 
-let () = InterpreterStdlib.init_default_env ()
+let () = Stdlib.init_default_env ()
 
 let rec repl env c =
   let () = printf ">>> "; Out_channel.flush Out_channel.stdout; in
@@ -14,7 +13,7 @@ let rec repl env c =
   | Some "exit" -> ()
   | Some l ->
     try
-      let vals = (parse_str l) in
+      let vals = (read_from_str l) in
       (* dbg_print_all vals; *)
       pretty_print_all (eval_all env vals);
       Out_channel.flush Out_channel.stdout;
@@ -23,7 +22,7 @@ let rec repl env c =
     | Invalid_argument s ->
       printf "%s\nResuming repl\n" s;
       repl env c
-    | Parser.Error ->
+    | Parser.Parse.Error ->
       printf "Expression '%s' couldn't be parsed, try again\n" l;
       repl env c
 ;;

dune-project

@@ -1,2 +1,5 @@
 (lang dune 3.7)
 (using menhir 2.1)
+
+(package
+ (name ollisp))

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1764950072,
+        "narHash": "sha256-BmPWzogsG2GsXZtlT+MTcAWeDK5hkbGRZTeZNW42fwA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "f61125a668a320878494449750330ca58b78c557",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,27 @@
+{
+  description = "a lisp interpreter/compiler in ocaml";
+  inputs =  {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs = {self, nixpkgs}: 
+  let
+    pkgs = nixpkgs.legacyPackages.x86_64-linux;
+  in
+  {
+    packages.x86_64-linux.default = pkgs.ocamlPackages.buildDunePackage {
+      pname = "ollisp";
+      version = "0.0.1";
+      src = pkgs.lib.cleanSource ./.;
+      preBuildPhase = "ls -R";
+      nativeBuildInputs = with pkgs; [
+        ocamlPackages.menhir
+      ];
+    };
+    devShells.x86_64-linux.default = pkgs.mkShell {
+      nativeBuildInputs = with pkgs.ocamlPackages; [
+        menhir merlin dune_3
+      ];
+    };
+  };
+}

lib/compiler/compilation.ml

@@ -0,0 +1,25 @@
+
+open Parser.Ast;;
+
+(* This type represents an intermediate step between the AST and opcodes in our
+   compiler. We need this extra step to resolve addresses, e.g. how do you know
+   what exact address an if expression needs to jump to before you compile it?
+   you don't, you just keep a symbolic label there, resolve later.
+ *)
+type intermediate_opcode =
+  | ISelect of string * string
+  | ILDF of string
+  | ILD of int (* an index into the constant table *)
+  | INil
+  | IRet
+  | IAdd
+  | IJoin
+  | ILabel of string (* does not emit any byte code *)
+
+
+
+
+(* TODO: Complete *)
+let (compile : lisp_ast -> intermediate_opcode list) = function
+  | LInt x -> [ILD x]
+  | _ -> [];;

lib/compiler/dune

@@ -0,0 +1,3 @@
+(library
+ (name compiler)
+ (libraries parser))

lib/dune

@@ -1,7 +0,0 @@
-(library
- (name lisp))
-
-(include_subdirs unqualified)
-
-(menhir (modules parser))
-(ocamllex lexer)

lib/interpreter/ast.ml

@@ -1,3 +1,17 @@
+
+(* This is different from the lisp_ast data returned by the parser!
+   We will first need to translate that into this in order to use it.
+   This representation includes things that can only occur during runtime,
+   like the various kinds of functions and macros.
+
+   Additionally, since this is an interpreter, macros tend to be a little
+   awkward in that they behave exactly like the macro gets expanded just
+   before the result gets executed. This is different from the compiled
+   behaviour where the macro is evaluated at compile time.
+
+   Though of course, with the dynamic nature of lisp, and its capability
+   to compile more code at runtime, there will naturally be complications.
+ *)
 type lisp_val = 
   | LInt of int 
   | LDouble of float 
@@ -17,7 +31,7 @@ type lisp_val =
   | LLambda of environment * lisp_val * lisp_val
   (* a macro is exactly the same as a function, with the distinction
      that it receives all of its arguments completely unevaluated
-  in a compiled lisp this would probably make more of a difference *)
+   *)
   | LMacro of string * environment * lisp_val * lisp_val
   | LUnnamedMacro of environment * lisp_val * lisp_val
   | LQuoted of lisp_val
@@ -113,3 +127,16 @@ let pretty_print_all vs =
 let dbg_print_all vs =
   let pr v = Printf.printf "%s\n" (dbg_print_one v) in
   List.iter pr vs
+
+
+let rec convert_one = function
+  | Parser.Ast.LInt x -> LInt x
+  | Parser.Ast.LDouble x -> LDouble x
+  | Parser.Ast.LNil -> LNil
+  | Parser.Ast.LString s -> LString s
+  | Parser.Ast.LSymbol s -> LSymbol s
+  | Parser.Ast.LCons (a, b) -> LCons (convert_one a, convert_one b)
+
+
+let read_from_str s =
+  List.map convert_one (Parser.parse_str s)

lib/interpreter/dune

@@ -0,0 +1,4 @@
+(library
+ (name interpreter)
+ (libraries parser)
+ (package ollisp))

lib/interpreter/stdlib.ml

@@ -200,5 +200,5 @@ let init_default_env () =
      Idea: maybe put this in a file instead of putting
      literally the entire standard library in a constant string
    *)
-  ignore (Eval.eval_all default_env (Read.parse_str init_script));
+  ignore (Eval.eval_all default_env (read_from_str init_script));
   ()

lib/parser/ast.ml

@@ -0,0 +1,10 @@
+
+
+type lisp_ast =
+  | LInt of int
+  | LDouble of float
+  | LSymbol of string
+  | LString of string
+  | LNil
+  | LCons of lisp_ast * lisp_ast
+

lib/parser/dune

@@ -0,0 +1,7 @@
+(library
+ (name parser)
+ (modules parser lex parse ast)
+ (package ollisp))
+
+(menhir (modules parse))
+(ocamllex lex)

lib/parser/lex.mll

@@ -1,6 +1,6 @@
 {
 open Lexing
-open Parser
+open Parse
 exception SyntaxError of string
 
 let strip_quotes s = String.sub s 1 (String.length s - 2);;

lib/parser/parse.mly

@@ -12,7 +12,7 @@
 %token DOT
 %token EOF
 
-%start <Ast.lisp_val option> prog
+%start <lisp_ast option> prog
 %%
 
 prog:
@@ -22,7 +22,7 @@ prog:
 
 expr:
   | i = INT { LInt i }
-  | d = DOUBLE {LDouble d}
+  | d = DOUBLE { LDouble d}
   | s = SYM { LSymbol s }
   | s = STR { LString (String.uppercase_ascii s) }
   | LPAREN; l = lisp_list_rest { l }

lib/parser/parser.ml

@@ -1,4 +1,4 @@
-let parse_one lb = Parser.prog (Lexer.read) lb
+let parse_one lb = Parse.prog (Lex.read) lb
 
 let parse lb = 
   let rec helper () =
@@ -11,3 +11,6 @@ let parse lb =
 let parse_str s =
   parse (Lexing.from_string s)
 
+
+module Ast = Ast
+module Parse = Parse