All: add keywords.

Also, fix nth and count to match cloure.

14 files changed, 121 insertions, 87 deletions

diff --git a/cs/core.cs b/cs/core.cs
index 8bbf6be..3e40681 100644
--- a/cs/core.cs
+++ b/cs/core.cs
@@ -35,6 +35,19 @@ namespace Mal {
         static MalFunc symbol_Q = new MalFunc(
             a => a[0] is MalSymbol ? True : False);
 
+        static MalFunc keyword = new MalFunc(
+            a => new MalString("\u029e" + ((MalString)a[0]).getValue()));
+
+        static MalFunc keyword_Q = new MalFunc(
+            a => {
+                if (a[0] is MalString &&
+                    ((MalString)a[0]).getValue()[0] == '\u029e') {
+                    return True;
+                } else {
+                    return False;
+                }
+            } );
+
 
         // Number functions
         static MalFunc time_ms = new MalFunc(
@@ -159,7 +172,15 @@ namespace Mal {
             });
 
         static MalFunc nth = new MalFunc(
-            a => ((MalList)a[0])[ (int)((MalInt)a[1]).getValue() ]);
+            a => {
+                var idx = (int)((MalInt)a[1]).getValue();
+                if (idx < ((MalList)a[0]).size()) {
+                    return ((MalList)a[0])[idx];
+                } else {
+                    throw new Mal.types.MalException(
+                        "nth: index out of range");
+                }
+            });
 
         static MalFunc first = new MalFunc(
             a => ((MalList)a[0])[0]);
@@ -171,7 +192,11 @@ namespace Mal {
             a => ((MalList)a[0]).size() == 0 ? True : False);
 
         static MalFunc count = new MalFunc(
-            a => new MalInt(((MalList)a[0]).size()));
+            a => {
+                return (a[0] == Nil)
+                    ? new MalInt(0)
+                    :new MalInt(((MalList)a[0]).size());
+            });
 
         static MalFunc conj = new MalFunc(
             a => {
@@ -254,6 +279,8 @@ namespace Mal {
             {"false?", false_Q},
             {"symbol", new MalFunc(a => new MalSymbol((MalString)a[0]))},
             {"symbol?", symbol_Q},
+            {"keyword", keyword},
+            {"keyword?", keyword_Q},
 
             {"pr-str", pr_str},
             {"str", str},
diff --git a/cs/env.cs b/cs/env.cs
index cb5318f..39ab100 100644
--- a/cs/env.cs
+++ b/cs/env.cs
@@ -26,8 +26,8 @@ namespace Mal {
                 }
             }
             
-            public Env find(string key) {
-                if (data.ContainsKey(key)) {
+            public Env find(MalSymbol key) {
+                if (data.ContainsKey(key.getName())) {
                     return this;
                 } else if (outer != null) {
                     return outer.find(key);
@@ -36,18 +36,18 @@ namespace Mal {
                 }
             }
 
-            public MalVal get(string key) {
+            public MalVal get(MalSymbol key) {
                 Env e = find(key);
                 if (e == null) {
                     throw new Mal.types.MalException(
-                            "'" + key + "' not found");
+                            "'" + key.getName() + "' not found");
                 } else {
-                    return e.data[key];
+                    return e.data[key.getName()];
                 }
             }
 
-            public Env set(string key, MalVal value) {
-                data[key] = value;
+            public Env set(MalSymbol key, MalVal value) {
+                data[key.getName()] = value;
                 return this;
             }
         }
diff --git a/cs/printer.cs b/cs/printer.cs
index b5e8c63..8b10dd1 100644
--- a/cs/printer.cs
+++ b/cs/printer.cs
@@ -20,7 +20,9 @@ namespace Mal {
                                 string delim, bool print_readably) {
             List<string> strs = new List<string>();
             foreach (KeyValuePair<string, MalVal> entry in value) {
-                if (print_readably) {
+                if (entry.Key.Length > 0 && entry.Key[0] == '\u029e') {
+                    strs.Add(":" + entry.Key.Substring(1));
+                } else if (print_readably) {
                     strs.Add("\"" + entry.Key.ToString() + "\"");
                 } else {
                     strs.Add(entry.Key.ToString());
diff --git a/cs/reader.cs b/cs/reader.cs
index dbc74af..10973aa 100644
--- a/cs/reader.cs
+++ b/cs/reader.cs
@@ -53,7 +53,7 @@ namespace Mal {
 
         public static MalVal read_atom(Reader rdr) {
             string token = rdr.next();
-            string pattern = @"(^-?[0-9]+$)|(^-?[0-9][0-9.]*$)|(^nil$)|(^true$)|(^false$)|^("".*"")$|(^[^""]*$)";
+            string pattern = @"(^-?[0-9]+$)|(^-?[0-9][0-9.]*$)|(^nil$)|(^true$)|(^false$)|^("".*"")$|:(.*)|(^[^""]*$)";
             Regex regex = new Regex(pattern);
             Match match = regex.Match(token);
             //Console.WriteLine("token: ^" + token + "$");
@@ -75,7 +75,9 @@ namespace Mal {
                     .Replace("\\n", "\n");
                 return new Mal.types.MalString(str);
             } else if (match.Groups[7].Value != String.Empty) {
-                return new Mal.types.MalSymbol(match.Groups[7].Value);
+                return new Mal.types.MalString("\u029e" + match.Groups[7].Value);
+            } else if (match.Groups[8].Value != String.Empty) {
+                return new Mal.types.MalSymbol(match.Groups[8].Value);
             } else {
                 throw new ParseError("unrecognized '" + match.Groups[0] + "'");
             }
diff --git a/cs/step2_eval.cs b/cs/step2_eval.cs
index 1e3866e..8c68336 100644
--- a/cs/step2_eval.cs
+++ b/cs/step2_eval.cs
@@ -45,7 +45,7 @@ namespace Mal {
 
         static MalVal EVAL(MalVal orig_ast, Dictionary<string, MalVal> env) {
             MalVal a0;
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
diff --git a/cs/step3_env.cs b/cs/step3_env.cs
index 9977811..6c4f2fe 100644
--- a/cs/step3_env.cs
+++ b/cs/step3_env.cs
@@ -22,8 +22,7 @@ namespace Mal {
         // eval
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -47,7 +46,7 @@ namespace Mal {
         static MalVal EVAL(MalVal orig_ast, Env env) {
             MalVal a0, a1, a2, res;
             MalList el;
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -66,7 +65,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -77,7 +76,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 return EVAL(a2, let_env);
             default:
@@ -96,10 +95,14 @@ namespace Mal {
         static void Main(string[] args) {
             var repl_env = new Mal.env.Env(null);
             Func<string, MalVal> RE = (string str) => EVAL(READ(str), repl_env);
-            repl_env.set("+", new MalFunc(a => (MalInt)a[0] + (MalInt)a[1]) );
-            repl_env.set("-", new MalFunc(a => (MalInt)a[0] - (MalInt)a[1]) );
-            repl_env.set("*", new MalFunc(a => (MalInt)a[0] * (MalInt)a[1]) );
-            repl_env.set("/", new MalFunc(a => (MalInt)a[0] / (MalInt)a[1]) );
+            repl_env.set(new MalSymbol("+"), new MalFunc(
+                        a => (MalInt)a[0] + (MalInt)a[1]) );
+            repl_env.set(new MalSymbol("-"), new MalFunc(
+                        a => (MalInt)a[0] - (MalInt)a[1]) );
+            repl_env.set(new MalSymbol("*"), new MalFunc(
+                        a => (MalInt)a[0] * (MalInt)a[1]) );
+            repl_env.set(new MalSymbol("/"), new MalFunc(
+                        a => (MalInt)a[0] / (MalInt)a[1]) );
 
             if (args.Length > 0 && args[0] == "--raw") {
                 Mal.readline.mode = Mal.readline.Mode.Raw;
diff --git a/cs/step4_if_fn_do.cs b/cs/step4_if_fn_do.cs
index ff8c3b9..aefe226 100644
--- a/cs/step4_if_fn_do.cs
+++ b/cs/step4_if_fn_do.cs
@@ -22,8 +22,7 @@ namespace Mal {
         // eval
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -47,7 +46,7 @@ namespace Mal {
         static MalVal EVAL(MalVal orig_ast, Env env) {
             MalVal a0, a1, a2, a3, res;
             MalList el;
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -65,7 +64,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -76,7 +75,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 return EVAL(a2, let_env);
             case "do":
@@ -123,7 +122,7 @@ namespace Mal {
             
             // core.cs: defined using C#
             foreach (var entry in core.ns) {
-                repl_env.set(entry.Key, entry.Value);
+                repl_env.set(new MalSymbol(entry.Key), entry.Value);
             }
 
             // core.mal: defined using the language itself
diff --git a/cs/step5_tco.cs b/cs/step5_tco.cs
index f1307f0..55d414a 100644
--- a/cs/step5_tco.cs
+++ b/cs/step5_tco.cs
@@ -22,8 +22,7 @@ namespace Mal {
         // eval
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -50,7 +49,7 @@ namespace Mal {
 
             while (true) {
 
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -68,7 +67,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -79,7 +78,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 orig_ast = a2;
                 env = let_env;
@@ -137,7 +136,7 @@ namespace Mal {
             
             // core.cs: defined using C#
             foreach (var entry in core.ns) {
-                repl_env.set(entry.Key, entry.Value);
+                repl_env.set(new MalSymbol(entry.Key), entry.Value);
             }
 
             // core.mal: defined using the language itself
diff --git a/cs/step6_file.cs b/cs/step6_file.cs
index c885922..a84e87c 100644
--- a/cs/step6_file.cs
+++ b/cs/step6_file.cs
@@ -23,8 +23,7 @@ namespace Mal {
         // eval
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -51,7 +50,7 @@ namespace Mal {
 
             while (true) {
 
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -69,7 +68,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -80,7 +79,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 orig_ast = a2;
                 env = let_env;
@@ -138,9 +137,10 @@ namespace Mal {
             
             // core.cs: defined using C#
             foreach (var entry in core.ns) {
-                repl_env.set(entry.Key, entry.Value);
+                repl_env.set(new MalSymbol(entry.Key), entry.Value);
             }
-            repl_env.set("eval", new MalFunc(a => EVAL(a[0], repl_env)));
+            repl_env.set(new MalSymbol("eval"), new MalFunc(
+                        a => EVAL(a[0], repl_env)));
             int fileIdx = 1;
             if (args.Length > 0 && args[0] == "--raw") {
                 Mal.readline.mode = Mal.readline.Mode.Raw;
@@ -150,7 +150,7 @@ namespace Mal {
             for (int i=fileIdx; i < args.Length; i++) {
                 _argv.conj_BANG(new MalString(args[i]));
             }
-            repl_env.set("*ARGV*", _argv);
+            repl_env.set(new MalSymbol("*ARGV*"), _argv);
 
             // core.mal: defined using the language itself
             RE("(def! not (fn* (a) (if a false true)))");
diff --git a/cs/step7_quote.cs b/cs/step7_quote.cs
index c25498f..7b03152 100644
--- a/cs/step7_quote.cs
+++ b/cs/step7_quote.cs
@@ -50,8 +50,7 @@ namespace Mal {
 
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -78,7 +77,7 @@ namespace Mal {
 
             while (true) {
 
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -96,7 +95,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -107,7 +106,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 orig_ast = a2;
                 env = let_env;
@@ -170,9 +169,10 @@ namespace Mal {
             
             // core.cs: defined using C#
             foreach (var entry in core.ns) {
-                repl_env.set(entry.Key, entry.Value);
+                repl_env.set(new MalSymbol(entry.Key), entry.Value);
             }
-            repl_env.set("eval", new MalFunc(a => EVAL(a[0], repl_env)));
+            repl_env.set(new MalSymbol("eval"), new MalFunc(
+                        a => EVAL(a[0], repl_env)));
             int fileIdx = 1;
             if (args.Length > 0 && args[0] == "--raw") {
                 Mal.readline.mode = Mal.readline.Mode.Raw;
@@ -182,7 +182,7 @@ namespace Mal {
             for (int i=fileIdx; i < args.Length; i++) {
                 _argv.conj_BANG(new MalString(args[i]));
             }
-            repl_env.set("*ARGV*", _argv);
+            repl_env.set(new MalSymbol("*ARGV*"), _argv);
 
             // core.mal: defined using the language itself
             RE("(def! not (fn* (a) (if a false true)))");
diff --git a/cs/step8_macros.cs b/cs/step8_macros.cs
index ccc0242..cac1411 100644
--- a/cs/step8_macros.cs
+++ b/cs/step8_macros.cs
@@ -52,8 +52,8 @@ namespace Mal {
             if (ast is MalList) {
                 MalVal a0 = ((MalList)ast)[0];
                 if (a0 is MalSymbol &&
-                    env.find(((MalSymbol)a0).getName()) != null) {
-                    MalVal mac = env.get(((MalSymbol)a0).getName());
+                    env.find((MalSymbol)a0) != null) {
+                    MalVal mac = env.get((MalSymbol)a0);
                     if (mac is MalFunc &&
                         ((MalFunc)mac).isMacro()) {
                         return true;
@@ -66,7 +66,7 @@ namespace Mal {
         public static MalVal macroexpand(MalVal ast, Env env) {
             while (is_macro_call(ast, env)) {
                 MalSymbol a0 = (MalSymbol)((MalList)ast)[0];
-                MalFunc mac = (MalFunc) env.get(a0.getName());
+                MalFunc mac = (MalFunc) env.get(a0);
                 ast = mac.apply(((MalList)ast).rest());
             }
             return ast;
@@ -74,8 +74,7 @@ namespace Mal {
 
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -102,7 +101,7 @@ namespace Mal {
 
             while (true) {
 
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -123,7 +122,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -134,7 +133,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 orig_ast = a2;
                 env = let_env;
@@ -149,7 +148,7 @@ namespace Mal {
                 a2 = ast[2];
                 res = EVAL(a2, env);
                 ((MalFunc)res).setMacro();
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set(((MalSymbol)a1), res);
                 return res;
             case "macroexpand":
                 a1 = ast[1];
@@ -207,9 +206,10 @@ namespace Mal {
             
             // core.cs: defined using C#
             foreach (var entry in core.ns) {
-                repl_env.set(entry.Key, entry.Value);
+                repl_env.set(new MalSymbol(entry.Key), entry.Value);
             }
-            repl_env.set("eval", new MalFunc(a => EVAL(a[0], repl_env)));
+            repl_env.set(new MalSymbol("eval"), new MalFunc(
+                        a => EVAL(a[0], repl_env)));
             int fileIdx = 1;
             if (args.Length > 0 && args[0] == "--raw") {
                 Mal.readline.mode = Mal.readline.Mode.Raw;
@@ -219,7 +219,7 @@ namespace Mal {
             for (int i=fileIdx; i < args.Length; i++) {
                 _argv.conj_BANG(new MalString(args[i]));
             }
-            repl_env.set("*ARGV*", _argv);
+            repl_env.set(new MalSymbol("*ARGV*"), _argv);
 
             // core.mal: defined using the language itself
             RE("(def! not (fn* (a) (if a false true)))");
diff --git a/cs/step9_try.cs b/cs/step9_try.cs
index 1d724d1..bea360c 100644
--- a/cs/step9_try.cs
+++ b/cs/step9_try.cs
@@ -52,8 +52,8 @@ namespace Mal {
             if (ast is MalList) {
                 MalVal a0 = ((MalList)ast)[0];
                 if (a0 is MalSymbol &&
-                    env.find(((MalSymbol)a0).getName()) != null) {
-                    MalVal mac = env.get(((MalSymbol)a0).getName());
+                    env.find((MalSymbol)a0) != null) {
+                    MalVal mac = env.get((MalSymbol)a0);
                     if (mac is MalFunc &&
                         ((MalFunc)mac).isMacro()) {
                         return true;
@@ -66,7 +66,7 @@ namespace Mal {
         public static MalVal macroexpand(MalVal ast, Env env) {
             while (is_macro_call(ast, env)) {
                 MalSymbol a0 = (MalSymbol)((MalList)ast)[0];
-                MalFunc mac = (MalFunc) env.get(a0.getName());
+                MalFunc mac = (MalFunc) env.get(a0);
                 ast = mac.apply(((MalList)ast).rest());
             }
             return ast;
@@ -74,8 +74,7 @@ namespace Mal {
 
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -102,7 +101,7 @@ namespace Mal {
 
             while (true) {
 
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -123,7 +122,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -134,7 +133,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 orig_ast = a2;
                 env = let_env;
@@ -149,7 +148,7 @@ namespace Mal {
                 a2 = ast[2];
                 res = EVAL(a2, env);
                 ((MalFunc)res).setMacro();
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set(((MalSymbol)a1), res);
                 return res;
             case "macroexpand":
                 a1 = ast[1];
@@ -228,9 +227,10 @@ namespace Mal {
             
             // core.cs: defined using C#
             foreach (var entry in core.ns) {
-                repl_env.set(entry.Key, entry.Value);
+                repl_env.set(new MalSymbol(entry.Key), entry.Value);
             }
-            repl_env.set("eval", new MalFunc(a => EVAL(a[0], repl_env)));
+            repl_env.set(new MalSymbol("eval"), new MalFunc(
+                        a => EVAL(a[0], repl_env)));
             int fileIdx = 1;
             if (args.Length > 0 && args[0] == "--raw") {
                 Mal.readline.mode = Mal.readline.Mode.Raw;
@@ -240,7 +240,7 @@ namespace Mal {
             for (int i=fileIdx; i < args.Length; i++) {
                 _argv.conj_BANG(new MalString(args[i]));
             }
-            repl_env.set("*ARGV*", _argv);
+            repl_env.set(new MalSymbol("*ARGV*"), _argv);
 
             // core.mal: defined using the language itself
             RE("(def! not (fn* (a) (if a false true)))");
diff --git a/cs/stepA_interop.cs b/cs/stepA_interop.cs
index f51f824..2e8fc12 100644
--- a/cs/stepA_interop.cs
+++ b/cs/stepA_interop.cs
@@ -52,8 +52,8 @@ namespace Mal {
             if (ast is MalList) {
                 MalVal a0 = ((MalList)ast)[0];
                 if (a0 is MalSymbol &&
-                    env.find(((MalSymbol)a0).getName()) != null) {
-                    MalVal mac = env.get(((MalSymbol)a0).getName());
+                    env.find((MalSymbol)a0) != null) {
+                    MalVal mac = env.get((MalSymbol)a0);
                     if (mac is MalFunc &&
                         ((MalFunc)mac).isMacro()) {
                         return true;
@@ -66,7 +66,7 @@ namespace Mal {
         public static MalVal macroexpand(MalVal ast, Env env) {
             while (is_macro_call(ast, env)) {
                 MalSymbol a0 = (MalSymbol)((MalList)ast)[0];
-                MalFunc mac = (MalFunc) env.get(a0.getName());
+                MalFunc mac = (MalFunc) env.get(a0);
                 ast = mac.apply(((MalList)ast).rest());
             }
             return ast;
@@ -74,8 +74,7 @@ namespace Mal {
 
         static MalVal eval_ast(MalVal ast, Env env) {
             if (ast is MalSymbol) {
-                MalSymbol sym = (MalSymbol)ast;
-                return env.get(sym.getName());
+                return env.get((MalSymbol)ast);
             } else if (ast is MalList) {
                 MalList old_lst = (MalList)ast;
                 MalList new_lst = ast.list_Q() ? new MalList()
@@ -102,7 +101,7 @@ namespace Mal {
 
             while (true) {
 
-            //System.out.println("EVAL: " + printer._pr_str(orig_ast, true));
+            //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
             if (!orig_ast.list_Q()) {
                 return eval_ast(orig_ast, env);
             }
@@ -123,7 +122,7 @@ namespace Mal {
                 a1 = ast[1];
                 a2 = ast[2];
                 res = EVAL(a2, env);
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set((MalSymbol)a1, res);
                 return res;
             case "let*":
                 a1 = ast[1];
@@ -134,7 +133,7 @@ namespace Mal {
                 for(int i=0; i<((MalList)a1).size(); i+=2) {
                     key = (MalSymbol)((MalList)a1)[i];
                     val = ((MalList)a1)[i+1];
-                    let_env.set(key.getName(), EVAL(val, let_env));
+                    let_env.set(key, EVAL(val, let_env));
                 }
                 orig_ast = a2;
                 env = let_env;
@@ -149,7 +148,7 @@ namespace Mal {
                 a2 = ast[2];
                 res = EVAL(a2, env);
                 ((MalFunc)res).setMacro();
-                env.set(((MalSymbol)a1).getName(), res);
+                env.set(((MalSymbol)a1), res);
                 return res;
             case "macroexpand":
                 a1 = ast[1];
@@ -228,9 +227,10 @@ namespace Mal {
             
             // core.cs: defined using C#
             foreach (var entry in core.ns) {
-                repl_env.set(entry.Key, entry.Value);
+                repl_env.set(new MalSymbol(entry.Key), entry.Value);
             }
-            repl_env.set("eval", new MalFunc(a => EVAL(a[0], repl_env)));
+            repl_env.set(new MalSymbol("eval"), new MalFunc(
+                        a => EVAL(a[0], repl_env)));
             int fileIdx = 1;
             if (args.Length > 0 && args[0] == "--raw") {
                 Mal.readline.mode = Mal.readline.Mode.Raw;
@@ -240,7 +240,7 @@ namespace Mal {
             for (int i=fileIdx; i < args.Length; i++) {
                 _argv.conj_BANG(new MalString(args[i]));
             }
-            repl_env.set("*ARGV*", _argv);
+            repl_env.set(new MalSymbol("*ARGV*"), _argv);
 
             // core.mal: defined using the language itself
             RE("(def! *host-language* \"c#\")");
diff --git a/cs/types.cs b/cs/types.cs
index c2f46c9..b96a9f4 100644
--- a/cs/types.cs
+++ b/cs/types.cs
@@ -160,7 +160,9 @@ namespace Mal {
                 return "\"" + value + "\"";
             }
             public override string ToString(bool print_readably) {
-                if (print_readably) {
+                if (value.Length > 0 && value[0] == '\u029e') {
+                    return ":" + value.Substring(1);
+                } else if (print_readably) {
                     return "\"" + value.Replace("\\", "\\\\")
                         .Replace("\"", "\\\"")
                         .Replace("\n", "\\n") + "\"";