Commit | Line | Data |
---|---|---|
3934e3f8 HT |
1 | import 'dart:io'; |
2 | ||
3 | import 'core.dart'; | |
4 | import 'env.dart'; | |
5 | import 'printer.dart' as printer; | |
6 | import 'reader.dart' as reader; | |
7 | import 'types.dart'; | |
8 | ||
9 | final Env replEnv = new Env(); | |
10 | ||
11 | void setupEnv(List<String> argv) { | |
12 | // TODO(het): use replEnv#set once generalized tearoffs are implemented | |
13 | ns.forEach((sym, fun) => replEnv.set(sym, fun)); | |
14 | ||
15 | replEnv.set(new MalSymbol('eval'), | |
16 | new MalBuiltin((List<MalType> args) => EVAL(args.single, replEnv))); | |
17 | ||
18 | replEnv.set(new MalSymbol('*ARGV*'), | |
19 | new MalList(argv.map((s) => new MalString(s)).toList())); | |
20 | ||
21 | rep('(def! not (fn* (a) (if a false true)))'); | |
22 | rep("(def! load-file " | |
23 | "(fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))"); | |
24 | } | |
25 | ||
26 | MalType quasiquote(MalType ast) { | |
27 | bool isPair(MalType ast) { | |
28 | return ast is MalIterable && ast.isNotEmpty; | |
29 | } | |
30 | ||
31 | if (!isPair(ast)) { | |
32 | return new MalList([new MalSymbol("quote"), ast]); | |
33 | } else { | |
34 | var list = ast as MalIterable; | |
35 | if (list.first == new MalSymbol("unquote")) { | |
36 | return list[1]; | |
37 | } else if (isPair(list.first) && | |
38 | (list.first as MalIterable).first == new MalSymbol("splice-unquote")) { | |
39 | return new MalList([ | |
40 | new MalSymbol("concat"), | |
41 | (list.first as MalIterable)[1], | |
42 | quasiquote(new MalList(list.sublist(1))) | |
43 | ]); | |
44 | } else { | |
45 | return new MalList([ | |
46 | new MalSymbol("cons"), | |
47 | quasiquote(list[0]), | |
48 | quasiquote(new MalList(list.sublist(1))) | |
49 | ]); | |
50 | } | |
51 | } | |
52 | } | |
53 | ||
54 | MalType READ(String x) => reader.read_str(x); | |
55 | ||
56 | MalType eval_ast(MalType ast, Env env) { | |
57 | if (ast is MalSymbol) { | |
58 | var result = env.get(ast); | |
59 | if (result == null) { | |
60 | throw new NotFoundException(ast.value); | |
61 | } | |
62 | return result; | |
63 | } else if (ast is MalList) { | |
64 | return new MalList(ast.elements.map((x) => EVAL(x, env)).toList()); | |
65 | } else if (ast is MalVector) { | |
66 | return new MalVector(ast.elements.map((x) => EVAL(x, env)).toList()); | |
67 | } else if (ast is MalHashMap) { | |
68 | var newMap = new Map<MalType, MalType>.from(ast.value); | |
69 | for (var key in newMap.keys) { | |
70 | newMap[key] = EVAL(newMap[key], env); | |
71 | } | |
72 | return new MalHashMap(newMap); | |
73 | } else { | |
74 | return ast; | |
75 | } | |
76 | } | |
77 | ||
78 | MalType EVAL(MalType ast, Env env) { | |
79 | while (true) { | |
80 | if (ast is! MalList) { | |
81 | return eval_ast(ast, env); | |
82 | } else { | |
83 | if ((ast as MalList).elements.isEmpty) { | |
84 | return ast; | |
85 | } else { | |
86 | var list = ast as MalList; | |
87 | if (list.elements.first is MalSymbol) { | |
88 | var symbol = list.elements.first as MalSymbol; | |
89 | var args = list.elements.sublist(1); | |
90 | if (symbol.value == "def!") { | |
91 | MalSymbol key = args.first; | |
92 | MalType value = EVAL(args[1], env); | |
93 | env.set(key, value); | |
94 | return value; | |
95 | } else if (symbol.value == "let*") { | |
96 | // TODO(het): If elements.length is not even, give helpful error | |
97 | Iterable<List<MalType>> pairs(List<MalType> elements) sync* { | |
98 | for (var i = 0; i < elements.length; i += 2) { | |
99 | yield [elements[i], elements[i + 1]]; | |
100 | } | |
101 | } | |
102 | ||
103 | var newEnv = new Env(env); | |
104 | MalIterable bindings = args.first; | |
105 | for (var pair in pairs(bindings.elements)) { | |
106 | MalSymbol key = pair[0]; | |
107 | MalType value = EVAL(pair[1], newEnv); | |
108 | newEnv.set(key, value); | |
109 | } | |
110 | ast = args[1]; | |
111 | env = newEnv; | |
112 | continue; | |
113 | } else if (symbol.value == "do") { | |
114 | eval_ast(new MalList(args.sublist(0, args.length - 1)), env); | |
115 | ast = args.last; | |
116 | continue; | |
117 | } else if (symbol.value == "if") { | |
118 | var condition = EVAL(args[0], env); | |
119 | if (condition is MalNil || | |
120 | condition is MalBool && condition.value == false) { | |
121 | // False side of branch | |
122 | if (args.length < 3) { | |
123 | return new MalNil(); | |
124 | } | |
125 | ast = args[2]; | |
126 | continue; | |
127 | } else { | |
128 | // True side of branch | |
129 | ast = args[1]; | |
130 | continue; | |
131 | } | |
132 | } else if (symbol.value == "fn*") { | |
133 | var params = (args[0] as MalIterable) | |
134 | .elements | |
135 | .map((e) => e as MalSymbol) | |
136 | .toList(); | |
137 | return new MalClosure( | |
138 | params, | |
139 | args[1], | |
140 | env, | |
141 | (List<MalType> funcArgs) => | |
142 | EVAL(args[1], new Env(env, params, funcArgs))); | |
143 | } else if (symbol.value == "quote") { | |
144 | return args.single; | |
145 | } else if (symbol.value == "quasiquote") { | |
146 | ast = quasiquote(args.first); | |
147 | continue; | |
148 | } | |
149 | } | |
150 | var newAst = eval_ast(ast, env) as MalList; | |
151 | var f = newAst.elements.first; | |
152 | var args = newAst.elements.sublist(1); | |
153 | if (f is MalBuiltin) { | |
154 | return f.call(args); | |
155 | } else if (f is MalClosure) { | |
156 | ast = f.ast; | |
157 | env = new Env(f.env, f.params, args); | |
158 | continue; | |
159 | } else { | |
160 | throw 'bad!'; | |
161 | } | |
162 | } | |
163 | } | |
164 | } | |
165 | } | |
166 | ||
167 | String PRINT(MalType x) => printer.pr_str(x); | |
168 | ||
169 | String rep(String x) { | |
dd7a4f55 | 170 | return PRINT(EVAL(READ(x), replEnv)); |
3934e3f8 HT |
171 | } |
172 | ||
173 | const prompt = 'user> '; | |
174 | main(List<String> args) { | |
175 | setupEnv(args.isEmpty ? const <String>[] : args.sublist(1)); | |
176 | if (args.isNotEmpty) { | |
177 | rep("(load-file \"${args.first}\")"); | |
178 | return; | |
179 | } | |
180 | while (true) { | |
181 | stdout.write(prompt); | |
182 | var input = stdin.readLineSync(); | |
183 | if (input == null) return; | |
184 | var output; | |
185 | try { | |
186 | output = rep(input); | |
dd7a4f55 JM |
187 | } on reader.ParseException catch (e) { |
188 | stdout.writeln("Error: '${e.message}'"); | |
189 | continue; | |
190 | } on NotFoundException catch (e) { | |
191 | stdout.writeln("Error: '${e.value}' not found"); | |
192 | continue; | |
193 | } on MalException catch (e) { | |
194 | stdout.writeln("Error: ${printer.pr_str(e.value)}"); | |
195 | continue; | |
3934e3f8 HT |
196 | } on reader.NoInputException { |
197 | continue; | |
198 | } | |
199 | stdout.writeln(output); | |
200 | } | |
201 | } |