cs/step4_if_fn_do.cs

   1 using System;
   2 using System.IO;
   3 using System.Collections;
   4 using System.Collections.Generic;
   5 using Mal;
   6 using MalVal = Mal.types.MalVal;
   7 using MalSymbol = Mal.types.MalSymbol;
   8 using MalInt = Mal.types.MalInt;
   9 using MalList = Mal.types.MalList;
  10 using MalVector = Mal.types.MalVector;
  11 using MalHashMap = Mal.types.MalHashMap;
  12 using MalFunc = Mal.types.MalFunc;
  13 using Env = Mal.env.Env;
  14
  15 namespace Mal {
  16     class step4_if_fn_do {
  17         // read
  18         static MalVal READ(string str) {
  19             return reader.read_str(str);
  20         }
  21
  22         // eval
  23         static MalVal eval_ast(MalVal ast, Env env) {
  24             if (ast is MalSymbol) {
  25                 return env.get((MalSymbol)ast);
  26             } else if (ast is MalList) {
  27                 MalList old_lst = (MalList)ast;
  28                 MalList new_lst = ast.list_Q() ? new MalList()
  29                                             : (MalList)new MalVector();
  30                 foreach (MalVal mv in old_lst.getValue()) {
  31                     new_lst.conj_BANG(EVAL(mv, env));
  32                 }
  33                 return new_lst;
  34             } else if (ast is MalHashMap) {
  35                 var new_dict = new Dictionary<string, MalVal>();
  36                 foreach (var entry in ((MalHashMap)ast).getValue()) {
  37                     new_dict.Add(entry.Key, EVAL((MalVal)entry.Value, env));
  38                 }
  39                 return new MalHashMap(new_dict);
  40             } else {
  41                 return ast;
  42             }
  43         }
  44
  45
  46         static MalVal EVAL(MalVal orig_ast, Env env) {
  47             MalVal a0, a1, a2, a3, res;
  48             MalList el;
  49             //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
  50             if (!orig_ast.list_Q()) {
  51                 return eval_ast(orig_ast, env);
  52             }
  53
  54             // apply list
  55             MalList ast = (MalList)orig_ast;
  56             if (ast.size() == 0) { return ast; }
  57             a0 = ast[0];
  58
  59             String a0sym = a0 is MalSymbol ? ((MalSymbol)a0).getName()
  60                                            : "__<*fn*>__";
  61
  62             switch (a0sym) {
  63             case "def!":
  64                 a1 = ast[1];
  65                 a2 = ast[2];
  66                 res = EVAL(a2, env);
  67                 env.set((MalSymbol)a1, res);
  68                 return res;
  69             case "let*":
  70                 a1 = ast[1];
  71                 a2 = ast[2];
  72                 MalSymbol key;
  73                 MalVal val;
  74                 Env let_env = new Env(env);
  75                 for(int i=0; i<((MalList)a1).size(); i+=2) {
  76                     key = (MalSymbol)((MalList)a1)[i];
  77                     val = ((MalList)a1)[i+1];
  78                     let_env.set(key, EVAL(val, let_env));
  79                 }
  80                 return EVAL(a2, let_env);
  81             case "do":
  82                 el = (MalList)eval_ast(ast.rest(), env);
  83                 return el[el.size()-1];
  84             case "if":
  85                 a1 = ast[1];
  86                 MalVal cond = EVAL(a1, env);
  87                 if (cond == Mal.types.Nil || cond == Mal.types.False) {
  88                     // eval false slot form
  89                     if (ast.size() > 3) {
  90                         a3 = ast[3];
  91                         return EVAL(a3, env);
  92                     } else {
  93                         return Mal.types.Nil;
  94                     }
  95                 } else {
  96                     // eval true slot form
  97                     a2 = ast[2];
  98                     return EVAL(a2, env);
  99                 }
 100             case "fn*":
 101                 MalList a1f = (MalList)ast[1];
 102                 MalVal a2f = ast[2];
 103                 Env cur_env = env;
 104                 return new MalFunc(
 105                     args => EVAL(a2f, new Env(cur_env, a1f, args)) );
 106             default:
 107                 el = (MalList)eval_ast(ast, env);
 108                 var f = (MalFunc)el[0];
 109                 return f.apply(el.rest());
 110             }
 111         }
 112
 113         // print
 114         static string PRINT(MalVal exp) {
 115             return printer._pr_str(exp, true);
 116         }
 117
 118         // repl
 119         static void Main(string[] args) {
 120             var repl_env = new Mal.env.Env(null);
 121             Func<string, MalVal> RE = (string str) => EVAL(READ(str), repl_env);
 122
 123             // core.cs: defined using C#
 124             foreach (var entry in core.ns) {
 125                 repl_env.set(new MalSymbol(entry.Key), entry.Value);
 126             }
 127
 128             // core.mal: defined using the language itself
 129             RE("(def! not (fn* (a) (if a false true)))");
 130
 131             if (args.Length > 0 && args[0] == "--raw") {
 132                 Mal.readline.mode = Mal.readline.Mode.Raw;
 133             }
 134
 135             // repl loop
 136             while (true) {
 137                 string line;
 138                 try {
 139                     line = Mal.readline.Readline("user> ");
 140                     if (line == null) { break; }
 141                     if (line == "") { continue; }
 142                 } catch (IOException e) {
 143                     Console.WriteLine("IOException: " + e.Message);
 144                     break;
 145                 }
 146                 try {
 147                     Console.WriteLine(PRINT(RE(line)));
 148                 } catch (Mal.types.MalContinue) {
 149                     continue;
 150                 } catch (Exception e) {
 151                     Console.WriteLine("Error: " + e.Message);
 152                     Console.WriteLine(e.StackTrace);
 153                     continue;
 154                 }
 155             }
 156         }
 157     }
 158 }