Ocaml: Add string functions

ocaml/Makefile

@@ -1,5 +1,6 @@
-STEPS = step0_repl.ml step1_read_print.ml step2_eval.ml step3_env.ml
-MODULES = types.ml reader.ml printer.ml env.ml
+STEPS = step0_repl.ml step1_read_print.ml step2_eval.ml step3_env.ml \
+        step4_if_fn_do.ml
+MODULES = types.ml reader.ml printer.ml env.ml core.ml
 LIBS = str.cmxa
 MAL_LIB = mal_lib.cmxa
 

ocaml/core.ml

@@ -28,5 +28,19 @@ let init env = begin
   Env.set env (Types.Symbol "=")
     (Types.Fn (function [a; b] -> Types.Bool (a = b) | _ -> Types.Bool false));
 
+  Env.set env (Types.Symbol "pr-str")
+    (Types.Fn (function xs ->
+      Types.String (Printer.join " " (List.map (fun s -> Printer.pr_str s true) xs))));
+  Env.set env (Types.Symbol "str")
+    (Types.Fn (function xs ->
+      Types.String (Printer.join "" (List.map (fun s -> Printer.pr_str s false) xs))));
+  Env.set env (Types.Symbol "prn")
+    (Types.Fn (function xs ->
+      print_endline (Printer.join " " (List.map (fun s -> Printer.pr_str s true) xs));
+      Types.Nil));
+  Env.set env (Types.Symbol "println")
+    (Types.Fn (function xs ->
+      print_endline (Printer.join " " (List.map (fun s -> Printer.pr_str s false) xs));
+      Types.Nil));
 end
 

ocaml/printer.ml

@@ -1,16 +1,18 @@
 let join sep xs =
   List.fold_left (fun a x -> if a = "" then x else a ^ sep ^ x) "" xs
 
-let rec pr_str mal_obj =
+let rec pr_str mal_obj print_readably =
   match mal_obj with
     | Types.Int i -> string_of_int i
     | Types.Symbol s -> s
     | Types.Keyword s -> ":" ^ s
     | Types.Nil -> "nil"
     | Types.Bool true -> "true"
     | Types.Bool false -> "false"
-    | Types.String s -> "\""
-                        ^ (Str.global_replace (Str.regexp "\"") "\\\"" s)
-                        ^ "\""
-    | Types.MalList xs -> "(" ^ (join " " (List.map pr_str xs)) ^ ")"
-    | Types.Fn f -> "<fn>"
+    | Types.String s ->
+        if print_readably
+	then  "\"" ^ (Str.global_replace (Str.regexp "\\([\"\\]\\)") "\\\\\\1" s) ^ "\""
+        else s
+    | Types.MalList xs ->
+        "(" ^ (join " " (List.map (fun s -> pr_str s print_readably) xs)) ^ ")"
+    | Types.Fn f -> "#<fn>"

ocaml/step1_read_print.ml

@@ -1,6 +1,6 @@
 let read str = Reader.read_str str
 let eval ast any = ast
-let print exp = Printer.pr_str exp
+let print exp = Printer.pr_str exp true
 let rep str = print (eval (read str) "")
 
 let rec main =

ocaml/step2_eval.ml

@@ -32,7 +32,7 @@ and eval ast env =
       | _ -> result
 
 let read str = Reader.read_str str
-let print exp = Printer.pr_str exp
+let print exp = Printer.pr_str exp true
 let rep str env = print (eval (read str) env)
 
 let rec main =

ocaml/step3_env.ml

@@ -39,7 +39,7 @@ and eval ast env =
     | _ -> eval_ast ast env
 
 let read str = Reader.read_str str
-let print exp = Printer.pr_str exp
+let print exp = Printer.pr_str exp true
 let rep str env = print (eval (read str) env)
 
 let rec main =

ocaml/step4_if_fn_do.ml

@@ -30,15 +30,15 @@ and eval ast env =
         Types.Fn
           (function args ->
             let sub_env = Env.make (Some env) in
-              let rec bind_args = (fun a b ->
+              let rec bind_args a b =
                 (match a, b with
                   | [Types.Symbol "&"; name], args -> Env.set sub_env name (Types.MalList 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);
+                  | _ -> raise (Invalid_argument "Bad param count in fn call"))
+              in bind_args arg_names args;
               eval expr sub_env)
     | Types.MalList _ ->
       (match eval_ast ast env with
@@ -47,7 +47,7 @@ and eval ast env =
     | _ -> eval_ast ast env
 
 let read str = Reader.read_str str
-let print exp = Printer.pr_str exp
+let print exp = Printer.pr_str exp true
 let rep str env = print (eval (read str) env)
 
 let rec main =

ocaml/types.ml

@@ -7,3 +7,7 @@ type mal_type =
   | Bool of bool
   | String of string
   | Fn of (mal_type list -> mal_type)
+
+let to_bool x = match x with
+  | Nil | Bool false -> false
+  | _ -> true