OCaml: self-hosting

4 files changed, 158 insertions, 4 deletions

diff --git a/ocaml/Makefile b/ocaml/Makefile
index a7c78fd..e5b0ac2 100644
--- a/ocaml/Makefile
+++ b/ocaml/Makefile
@@ -1,6 +1,6 @@
 STEPS = step0_repl.ml step1_read_print.ml step2_eval.ml step3_env.ml \
         step4_if_fn_do.ml step5_tco.ml step6_file.ml step7_quote.ml \
-	step8_macros.ml step9_try.ml
+	step8_macros.ml step9_try.ml stepA_interop.ml
 MODULES = types.ml reader.ml printer.ml env.ml core.ml
 LIBS = str.cmxa
 MAL_LIB = mal_lib.cmxa
diff --git a/ocaml/core.ml b/ocaml/core.ml
index 49041d8..19763fa 100644
--- a/ocaml/core.ml
+++ b/ocaml/core.ml
@@ -49,6 +49,9 @@ let rec conj = function
   | _ -> T.Nil
 
 let init env = begin
+  Env.set env (Types.symbol "throw")
+          (Types.fn (function [ast] -> raise (Types.MalExn ast) | _ -> T.Nil));
+
   Env.set env (Types.symbol "+")  (num_fun mk_int  ( +  ));
   Env.set env (Types.symbol "-")  (num_fun mk_int  ( -  ));
   Env.set env (Types.symbol "*")  (num_fun mk_int  ( *  ));
@@ -67,7 +70,10 @@ let init env = begin
   Env.set env (Types.symbol "empty?")
     (Types.fn (function [T.List {T.value = []}] -> T.Bool true | _ -> T.Bool false));
   Env.set env (Types.symbol "count")
-    (Types.fn (function [T.List {T.value = xs}] -> T.Int (List.length xs) | _ -> T.Int 0));
+    (Types.fn (function
+                | [T.List   {T.value = xs}]
+                | [T.Vector {T.value = xs}] -> T.Int (List.length xs)
+                | _ -> T.Int 0));
   Env.set env (Types.symbol "=")
     (Types.fn (function
                 | [T.List a; T.Vector b] -> T.Bool (a = b)
@@ -184,6 +190,8 @@ let init env = begin
                 | _ -> T.Bool false));
   Env.set env (Types.symbol "conj") (Types.fn conj);
 
+  Env.set env (Types.symbol "atom?")
+          (Types.fn (function [T.Atom _] -> T.Bool true | _ -> T.Bool false));
   Env.set env (Types.symbol "atom")
           (Types.fn (function [x] -> T.Atom (ref x) | _ -> T.Nil));
   Env.set env (Types.symbol "deref")
diff --git a/ocaml/step9_try.ml b/ocaml/step9_try.ml
index 462ab3a..37c41ac 100644
--- a/ocaml/step9_try.ml
+++ b/ocaml/step9_try.ml
@@ -90,8 +90,6 @@ and eval ast env =
        eval (quasiquote ast) env
     | T.List { T.value = [T.Symbol { T.value = "macroexpand" }; ast] } ->
        macroexpand ast env
-    | T.List { T.value = [T.Symbol { T.value = "throw" }; ast] } ->
-       raise (Types.MalExn (eval ast env))
     | T.List { T.value = [T.Symbol { T.value = "try*" }; scary ;
                           T.List { T.value = [T.Symbol { T.value = "catch*" };
                                               local ; handler]}]} ->
diff --git a/ocaml/stepA_interop.ml b/ocaml/stepA_interop.ml
new file mode 100644
index 0000000..1b2e98d
--- /dev/null
+++ b/ocaml/stepA_interop.ml
@@ -0,0 +1,148 @@
+module T = Types.Types
+
+let repl_env = Env.make (Some Core.ns)
+
+let rec quasiquote ast =
+  match ast with
+    | T.List   { T.value = [T.Symbol {T.value = "unquote"}; ast] } -> ast
+    | T.Vector { T.value = [T.Symbol {T.value = "unquote"}; ast] } -> ast
+    | T.List   { T.value = T.List { T.value = [T.Symbol {T.value = "splice-unquote"}; head]} :: tail }
+    | T.Vector { T.value = T.List { T.value = [T.Symbol {T.value = "splice-unquote"}; head]} :: tail } ->
+       Types.list [Types.symbol "concat"; head; quasiquote (Types.list tail)]
+    | T.List   { T.value = head :: tail }
+    | T.Vector { T.value = head :: tail } ->
+       Types.list [Types.symbol "cons"; quasiquote head; quasiquote (Types.list tail) ]
+    | ast -> Types.list [Types.symbol "quote"; ast]
+
+let rec macroexpand ast env =
+  match ast with
+  | T.List { T.value = s :: args } ->
+     (match (try Env.get env s with _ -> T.Nil) with
+      | T.Fn { T.value = f; T.is_macro = true } -> macroexpand (f args) env
+      | _ -> ast)
+  | _ -> ast
+
+let rec eval_ast ast env =
+  match ast with
+    | T.Symbol s -> Env.get env ast
+    | T.List { T.value = xs; T.meta = meta }
+      -> T.List { T.value = (List.map (fun x -> eval x env) xs);
+                  T.meta = meta;
+                  T.is_macro = false}
+    | T.Vector { T.value = xs; T.meta = meta }
+      -> T.Vector { T.value = (List.map (fun x -> eval x env) xs);
+                    T.meta = meta;
+                    T.is_macro = false}
+    | T.Map { T.value = xs; T.meta = meta }
+      -> T.Map {T.meta = meta;
+                T.is_macro = false;
+                T.value = (Types.MalMap.fold
+                             (fun k v m
+                              -> Types.MalMap.add (eval k env) (eval v env) m)
+                             xs
+                             Types.MalMap.empty)}
+    | _ -> ast
+and eval ast env =
+  match macroexpand ast env with
+    | T.List { T.value = [(T.Symbol { T.value = "def!" }); key; expr] } ->
+        let value = (eval expr env) in
+          Env.set env key value; value
+    | T.List { T.value = [(T.Symbol { T.value = "defmacro!" }); key; expr] } ->
+       (match (eval expr env) with
+          | T.Fn { T.value = f; T.meta = meta } ->
+             let fn = T.Fn { T.value = f; is_macro = true; meta = meta } in
+             Env.set env key fn; fn
+          | _ -> raise (Invalid_argument "devmacro! value must be a fn"))
+    | T.List { T.value = [(T.Symbol { T.value = "let*" }); (T.Vector { T.value = bindings }); body] }
+    | T.List { T.value = [(T.Symbol { T.value = "let*" }); (T.List   { T.value = bindings }); body] } ->
+        (let sub_env = Env.make (Some env) in
+          let rec bind_pairs = (function
+            | sym :: expr :: more ->
+                Env.set sub_env sym (eval expr sub_env);
+                bind_pairs more
+            | _::[] -> raise (Invalid_argument "let* bindings must be an even number of forms")
+            | [] -> ())
+            in bind_pairs bindings;
+          eval body sub_env)
+    | T.List { T.value = ((T.Symbol { T.value = "do" }) :: body) } ->
+        List.fold_left (fun x expr -> eval expr env) T.Nil body
+    | T.List { T.value = [T.Symbol { T.value = "if" }; test; then_expr; else_expr] } ->
+        if Types.to_bool (eval test env) then (eval then_expr env) else (eval else_expr env)
+    | T.List { T.value = [T.Symbol { T.value = "if" }; test; then_expr] } ->
+        if Types.to_bool (eval test env) then (eval then_expr env) else T.Nil
+    | T.List { T.value = [T.Symbol { T.value = "fn*" }; T.Vector { T.value = arg_names }; expr] }
+    | T.List { T.value = [T.Symbol { T.value = "fn*" }; T.List   { T.value = arg_names }; expr] } ->
+        Types.fn
+          (function args ->
+            let sub_env = Env.make (Some env) in
+              let rec bind_args a b =
+                (match a, b with
+                  | [T.Symbol { T.value = "&" }; name], args -> Env.set sub_env name (Types.list args);
+                  | (name :: names), (arg :: args) ->
+                      Env.set sub_env name arg;
+                      bind_args names args;
+                  | [], [] -> ()
+                  | _ -> raise (Invalid_argument "Bad param count in fn call"))
+              in bind_args arg_names args;
+              eval expr sub_env)
+    | T.List { T.value = [T.Symbol { T.value = "quote" }; ast] } -> ast
+    | T.List { T.value = [T.Symbol { T.value = "quasiquote" }; ast] } ->
+       eval (quasiquote ast) env
+    | T.List { T.value = [T.Symbol { T.value = "macroexpand" }; ast] } ->
+       macroexpand ast env
+    | T.List { T.value = [T.Symbol { T.value = "try*" }; scary ;
+                          T.List { T.value = [T.Symbol { T.value = "catch*" };
+                                              local ; handler]}]} ->
+       (try (eval scary env)
+        with exn ->
+           let value = match exn with
+             | Types.MalExn value -> value
+             | Invalid_argument msg -> T.String msg
+             | _ -> (T.String "OCaml exception") in
+           let sub_env = Env.make (Some env) in
+           Env.set sub_env local value;
+           eval handler sub_env)
+    | T.List _ as ast ->
+      (match eval_ast ast env with
+         | T.List { T.value = ((T.Fn { T.value = f }) :: args) } -> f args
+         | _ -> raise (Invalid_argument "Cannot invoke non-function"))
+    | ast -> eval_ast ast env
+
+let read str = Reader.read_str str
+let print exp = Printer.pr_str exp true
+let rep str env = print (eval (read str) env)
+
+let rec main =
+  try
+    Core.init Core.ns;
+    Env.set repl_env (Types.symbol "*ARGV*")
+            (Types.list (if Array.length Sys.argv > 1
+                         then (List.map (fun x -> T.String x) (List.tl (List.tl (Array.to_list Sys.argv))))
+                         else []));
+    Env.set repl_env (Types.symbol "eval")
+            (Types.fn (function [ast] -> eval ast repl_env | _ -> T.Nil));
+
+    ignore (rep "(def! *host-language* \"ocaml\")" repl_env);
+    ignore (rep "(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))" repl_env);
+    ignore (rep "(def! not (fn* (a) (if a false true)))" repl_env);
+    ignore (rep "(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))" repl_env);
+    ignore (rep "(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))" repl_env);
+
+    if Array.length Sys.argv > 1 then
+      ignore (rep ("(load-file \"" ^ Sys.argv.(1) ^ "\")") repl_env)
+    else
+      ignore (rep "(println (str \"Mal [\" *host-language* \"]\"))" repl_env);
+      while true do
+        print_string "user> ";
+        let line = read_line () in
+        try
+          print_endline (rep line repl_env);
+        with End_of_file -> ()
+           | Invalid_argument x ->
+              output_string stderr ("Invalid_argument exception: " ^ x ^ "\n");
+              flush stderr
+           | _ ->
+              output_string stderr ("Erroringness!\n");
+              flush stderr
+      done
+  with End_of_file -> ()