mirror of
https://github.com/kanaka/mal.git
synced 2024-11-10 12:47:45 +03:00
102 lines
2.9 KiB
JavaScript
102 lines
2.9 KiB
JavaScript
import { readline } from './node_readline'
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import { _symbol, _symbol_Q, _list_Q, _vector, _vector_Q,
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_hash_map_Q, _malfunc, _malfunc_Q } from './types'
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import { BlankException, read_str } from './reader'
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import { pr_str } from './printer'
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import { new_env, env_set, env_get } from './env'
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import { core_ns } from './core'
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// read
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const READ = (str) => read_str(str)
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// eval
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const eval_ast = (ast, env) => {
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if (_symbol_Q(ast)) {
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return env_get(env, ast)
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} else if (_list_Q(ast)) {
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return ast.map((x) => EVAL(x, env))
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} else if (_vector_Q(ast)) {
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return _vector(...ast.map((x) => EVAL(x, env)))
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} else if (_hash_map_Q(ast)) {
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let new_hm = new Map()
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for (let [k, v] of ast) {
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new_hm.set(EVAL(k, env), EVAL(v, env))
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}
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return new_hm
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} else {
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return ast
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}
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}
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const EVAL = (ast, env) => {
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while (true) {
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//console.log('EVAL:', pr_str(ast, true))
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if (!_list_Q(ast)) { return eval_ast(ast, env) }
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if (ast.length === 0) { return ast }
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const [a0, a1, a2, a3] = ast
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const a0sym = _symbol_Q(a0) ? Symbol.keyFor(a0) : Symbol(':default')
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switch (a0sym) {
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case 'def!':
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return env_set(env, a1, EVAL(a2, env))
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case 'let*':
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let let_env = new_env(env)
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for (let i=0; i < a1.length; i+=2) {
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env_set(let_env, a1[i], EVAL(a1[i+1], let_env))
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}
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env = let_env
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ast = a2
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break; // continue TCO loop
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case 'do':
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eval_ast(ast.slice(1,-1), env)
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ast = ast[ast.length-1]
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break; // continue TCO loop
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case 'if':
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let cond = EVAL(a1, env)
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if (cond === null || cond === false) {
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ast = (typeof a3 !== 'undefined') ? a3 : null
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} else {
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ast = a2
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}
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break; // continue TCO loop
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case 'fn*':
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return _malfunc((...args) => EVAL(a2, new_env(env, a1, args)),
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a2, env, a1)
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default:
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let [f, ...args] = eval_ast(ast, env)
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if (_malfunc_Q(f)) {
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env = new_env(f.env, f.params, args)
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ast = f.ast
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break; // continue TCO loop
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} else {
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return f(...args)
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}
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}
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}
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}
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// print
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const PRINT = (exp) => pr_str(exp, true)
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// repl
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let repl_env = new_env()
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const REP = (str) => PRINT(EVAL(READ(str), repl_env))
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// core.EXT: defined using ES6
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for (let [k, v] of core_ns) { env_set(repl_env, _symbol(k), v) }
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// core.mal: defined using language itself
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REP('(def! not (fn* (a) (if a false true)))')
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while (true) {
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let line = readline('user> ')
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if (line == null) break
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try {
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if (line) { console.log(REP(line)); }
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} catch (exc) {
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if (exc instanceof BlankException) { continue; }
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if (exc.stack) { console.log(exc.stack); }
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else { console.log(`Error: ${exc}`); }
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}
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}
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