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1 | import rl from './node_readline.js' |
2 | const readline = rl.readline | |
a05c086f | 3 | import { _list_Q, _malfunc, _malfunc_Q } from './types' |
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4 | import { BlankException, read_str } from './reader' |
5 | import { pr_str } from './printer' | |
6 | import { new_env, env_set, env_get } from './env' | |
7 | import { core_ns } from './core' | |
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8 | |
9 | // read | |
a05c086f | 10 | const READ = str => read_str(str) |
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11 | |
12 | // eval | |
a05c086f | 13 | const is_pair = x => Array.isArray(x) && x.length > 0 |
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14 | |
15 | const quasiquote = ast => { | |
16 | if (!is_pair(ast)) { | |
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17 | return [Symbol.for('quote'), ast] |
18 | } else if (ast[0] === Symbol.for('unquote')) { | |
4f8c7db9 | 19 | return ast[1] |
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20 | } else if (is_pair(ast[0]) && ast[0][0] === Symbol.for('splice-unquote')) { |
21 | return [Symbol.for('concat'), | |
22 | ast[0][1], | |
23 | quasiquote(ast.slice(1))] | |
e5c4e656 | 24 | } else { |
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25 | return [Symbol.for('cons'), |
26 | quasiquote(ast[0]), | |
27 | quasiquote(ast.slice(1))] | |
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28 | } |
29 | } | |
30 | ||
e5c4e656 | 31 | function macroexpand(ast, env) { |
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32 | while (_list_Q(ast) && typeof ast[0] === 'symbol' && ast[0] in env) { |
33 | let f = env_get(env, ast[0]) | |
34 | if (!f.ismacro) { break } | |
35 | ast = f(...ast.slice(1)) | |
e5c4e656 | 36 | } |
4f8c7db9 | 37 | return ast |
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38 | } |
39 | ||
40 | ||
41 | const eval_ast = (ast, env) => { | |
a05c086f | 42 | if (typeof ast === 'symbol') { |
e5c4e656 | 43 | return env_get(env, ast) |
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44 | } else if (ast instanceof Array) { |
45 | return ast.map(x => EVAL(x, env)) | |
46 | } else if (ast instanceof Map) { | |
4f8c7db9 | 47 | let new_hm = new Map() |
a05c086f | 48 | ast.forEach((v, k) => new_hm.set(EVAL(k, env), EVAL(v, env))) |
4f8c7db9 | 49 | return new_hm |
e5c4e656 | 50 | } else { |
4f8c7db9 | 51 | return ast |
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52 | } |
53 | } | |
54 | ||
55 | const EVAL = (ast, env) => { | |
56 | while (true) { | |
4f8c7db9 | 57 | //console.log('EVAL:', pr_str(ast, true)) |
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58 | if (!_list_Q(ast)) { return eval_ast(ast, env) } |
59 | ||
4f8c7db9 | 60 | ast = macroexpand(ast, env) |
bfa3dd35 | 61 | if (!_list_Q(ast)) { return eval_ast(ast, env) } |
f8665761 | 62 | if (ast.length === 0) { return ast } |
e5c4e656 | 63 | |
4f8c7db9 | 64 | const [a0, a1, a2, a3] = ast |
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65 | switch (typeof a0 === 'symbol' ? Symbol.keyFor(a0) : Symbol(':default')) { |
66 | case 'def!': | |
4f8c7db9 | 67 | return env_set(env, a1, EVAL(a2, env)) |
e5c4e656 | 68 | case 'let*': |
4f8c7db9 | 69 | let let_env = new_env(env) |
e5c4e656 | 70 | for (let i=0; i < a1.length; i+=2) { |
4f8c7db9 | 71 | env_set(let_env, a1[i], EVAL(a1[i+1], let_env)) |
e5c4e656 | 72 | } |
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73 | env = let_env |
74 | ast = a2 | |
a05c086f | 75 | break // continue TCO loop |
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76 | case 'quote': |
77 | return a1 | |
78 | case 'quasiquote': | |
79 | ast = quasiquote(a1) | |
a05c086f | 80 | break // continue TCO loop |
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81 | case 'defmacro!': |
82 | let func = EVAL(a2, env) | |
83 | func.ismacro = true | |
84 | return env_set(env, a1, func) | |
85 | case 'macroexpand': | |
86 | return macroexpand(a1, env) | |
87 | case 'try*': | |
e5c4e656 | 88 | try { |
4f8c7db9 | 89 | return EVAL(a1, env) |
e5c4e656 | 90 | } catch (exc) { |
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91 | if (a2 && a2[0] === Symbol.for('catch*')) { |
92 | if (exc instanceof Error) { exc = exc.message } | |
4f8c7db9 | 93 | return EVAL(a2[2], new_env(env, [a2[1]], [exc])) |
e5c4e656 | 94 | } else { |
4f8c7db9 | 95 | throw exc |
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96 | } |
97 | } | |
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98 | case 'do': |
99 | eval_ast(ast.slice(1,-1), env) | |
100 | ast = ast[ast.length-1] | |
a05c086f | 101 | break // continue TCO loop |
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102 | case 'if': |
103 | let cond = EVAL(a1, env) | |
e5c4e656 | 104 | if (cond === null || cond === false) { |
4f8c7db9 | 105 | ast = (typeof a3 !== 'undefined') ? a3 : null |
e5c4e656 | 106 | } else { |
4f8c7db9 | 107 | ast = a2 |
e5c4e656 | 108 | } |
a05c086f | 109 | break // continue TCO loop |
4f8c7db9 | 110 | case 'fn*': |
e5c4e656 | 111 | return _malfunc((...args) => EVAL(a2, new_env(env, a1, args)), |
a05c086f | 112 | a2, env, a1) |
e5c4e656 | 113 | default: |
4f8c7db9 | 114 | let [f, ...args] = eval_ast(ast, env) |
e5c4e656 | 115 | if (_malfunc_Q(f)) { |
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116 | env = new_env(f.env, f.params, args) |
117 | ast = f.ast | |
a05c086f | 118 | break // continue TCO loop |
e5c4e656 | 119 | } else { |
4f8c7db9 | 120 | return f(...args) |
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121 | } |
122 | } | |
123 | } | |
124 | } | |
125 | ||
126 | ||
a05c086f | 127 | const PRINT = exp => pr_str(exp, true) |
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128 | |
129 | // repl | |
4f8c7db9 | 130 | let repl_env = new_env() |
a05c086f | 131 | const REP = str => PRINT(EVAL(READ(str), repl_env)) |
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132 | |
133 | // core.EXT: defined using ES6 | |
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134 | for (let [k, v] of core_ns) { env_set(repl_env, Symbol.for(k), v) } |
135 | env_set(repl_env, Symbol.for('eval'), a => EVAL(a, repl_env)) | |
136 | env_set(repl_env, Symbol.for('*ARGV*'), []) | |
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137 | |
138 | // core.mal: defined using language itself | |
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139 | REP('(def! *host-language* "ecmascript6")') |
140 | REP('(def! not (fn* (a) (if a false true)))') | |
141 | REP('(def! load-file (fn* (f) (eval (read-string (str "(do " (slurp f) ")")))))') | |
142 | 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)))))))') | |
e5c4e656 | 143 | |
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144 | if (process.argv.length > 2) { |
145 | env_set(repl_env, Symbol.for('*ARGV*'), process.argv.slice(3)) | |
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146 | REP(`(load-file "${process.argv[2]}")`) |
147 | process.exit(0) | |
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148 | } |
149 | ||
4f8c7db9 | 150 | REP('(println (str "Mal [" *host-language* "]"))') |
e5c4e656 | 151 | while (true) { |
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152 | let line = readline('user> ') |
153 | if (line == null) break | |
e5c4e656 | 154 | try { |
a05c086f | 155 | if (line) { console.log(REP(line)) } |
e5c4e656 | 156 | } catch (exc) { |
a05c086f | 157 | if (exc instanceof BlankException) { continue } |
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158 | if (exc instanceof Error) { console.warn(exc.stack) } |
159 | else { console.warn(`Error: ${pr_str(exc, true)}`) } | |
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160 | } |
161 | } |