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See issue #587. * Merge eval-ast and eval into a single conditional. * Expand macros during the apply phase, removing lots of duplicate tests, and increasing the overall consistency by allowing the macro to be computed instead of referenced by name (`((defmacro! cond (...)))` is currently illegal for example). * Print "EVAL: $ast" at the top of EVAL if DEBUG-EVAL exists in the MAL environment. * Remove macroexpand and quasiquoteexpand special forms. * Use pattern-matching style in process/step*.txt. Unresolved issues: c.2: unable to reproduce with gcc 11.12.0. elm: the directory is unchanged. groovy: sometimes fail, but not on each rebuild. nasm: fails some new soft tests, but the issue is unreproducible when running the interpreter manually. objpascal: unreproducible with fpc 3.2.2. ocaml: unreproducible with 4.11.1. perl6: unreproducible with rakudo 2021.09. Unrelated changes: Reduce diff betweens steps. Prevent defmacro! from mutating functions: c forth logo miniMAL vb. dart: fix recent errors and warnings ocaml: remove metadata from symbols. Improve the logo implementation. Encapsulate all representation in types.lg and env.lg, unwrap numbers. Replace some manual iterations with logo control structures. Reduce the diff between steps. Use native iteration in env_get and env_map Rewrite the reader with less temporary strings. Reduce the number of temporary lists (for example, reverse iteration with butlast requires O(n^2) allocations). It seems possible to remove a few exceptions: GC settings (Dockerfile), NO_SELF_HOSTING (IMPLS.yml) and step5_EXCLUDES (Makefile.impls) .
193 lines
5.8 KiB
JavaScript
193 lines
5.8 KiB
JavaScript
if (typeof module !== 'undefined') {
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var types = require('./types');
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var readline = require('./node_readline');
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var reader = require('./reader');
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var printer = require('./printer');
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var Env = require('./env').Env;
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var core = require('./core');
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}
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// read
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function READ(str) {
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return reader.read_str(str);
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}
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// eval
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function qqLoop (acc, elt) {
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if (types._list_Q(elt) && elt.length
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&& types._symbol_Q(elt[0]) && elt[0].value == 'splice-unquote') {
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return [types._symbol("concat"), elt[1], acc];
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} else {
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return [types._symbol("cons"), quasiquote (elt), acc];
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}
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}
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function quasiquote(ast) {
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if (types._list_Q(ast) && 0<ast.length
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&& types._symbol_Q(ast[0]) && ast[0].value == 'unquote') {
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return ast[1];
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} else if (types._list_Q(ast)) {
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return ast.reduceRight(qqLoop,[]);
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} else if (types._vector_Q(ast)) {
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return [types._symbol("vec"), ast.reduceRight(qqLoop,[])];
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} else if (types._symbol_Q(ast) || types._hash_map_Q(ast)) {
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return [types._symbol("quote"), ast];
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} else {
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return ast;
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}
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}
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function _EVAL(ast, env) {
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while (true) {
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// Show a trace if DEBUG-EVAL is enabled.
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var dbgevalenv = env.find("DEBUG-EVAL");
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if (dbgevalenv !== null) {
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var dbgeval = env.get("DEBUG-EVAL");
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if (dbgeval !== null && dbgeval !== false)
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printer.println("EVAL:", printer._pr_str(ast, true));
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}
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// Non-list types.
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if (types._symbol_Q(ast)) {
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return env.get(ast.value);
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} else if (types._list_Q(ast)) {
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// Exit this switch.
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} else if (types._vector_Q(ast)) {
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var v = ast.map(function(a) { return EVAL(a, env); });
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v.__isvector__ = true;
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return v;
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} else if (types._hash_map_Q(ast)) {
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var new_hm = {};
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for (k in ast) {
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new_hm[k] = EVAL(ast[k], 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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// apply list
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if (ast.length === 0) {
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return ast;
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}
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var a0 = ast[0], a1 = ast[1], a2 = ast[2], a3 = ast[3];
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switch (a0.value) {
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case "def!":
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var res = EVAL(a2, env);
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if (!a1.constructor || a1.constructor.name !== 'Symbol') {
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throw new Error("env.get key must be a symbol")
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}
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return env.set(a1.value, res);
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case "let*":
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var let_env = new Env(env);
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for (var i=0; i < a1.length; i+=2) {
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if (!a1[i].constructor || a1[i].constructor.name !== 'Symbol') {
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throw new Error("env.get key must be a symbol")
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}
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let_env.set(a1[i].value, EVAL(a1[i+1], let_env));
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}
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ast = a2;
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env = let_env;
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break;
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case "quote":
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return a1;
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case "quasiquote":
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ast = quasiquote(a1);
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break;
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case 'defmacro!':
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var func = types._clone(EVAL(a2, env));
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func._ismacro_ = true;
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if (!a1.constructor || a1.constructor.name !== 'Symbol') {
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throw new Error("env.get key must be a symbol")
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}
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return env.set(a1.value, func);
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case "try*":
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try {
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return EVAL(a1, env);
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} catch (exc) {
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if (a2 && a2[0].value === "catch*") {
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if (exc instanceof Error) { exc = exc.message; }
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return EVAL(a2[2], new Env(env, [a2[1]], [exc]));
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} else {
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throw exc;
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}
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}
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case "do":
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for (var i=1; i < ast.length - 1; i++) {
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EVAL(ast[i], env);
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}
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ast = ast[ast.length-1];
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break;
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case "if":
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var 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;
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case "fn*":
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return types._function(EVAL, Env, a2, env, a1);
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default:
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var f = EVAL(a0, env);
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if (f._ismacro_) {
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ast = f.apply(f, ast.slice(1));
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break;
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}
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var args = ast.slice(1).map(function(a) { return EVAL(a, env); });
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if (f.__ast__) {
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ast = f.__ast__;
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env = f.__gen_env__(args);
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} else {
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return f.apply(f, args);
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}
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}
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}
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}
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function EVAL(ast, env) {
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var result = _EVAL(ast, env);
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return (typeof result !== "undefined") ? result : null;
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}
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// print
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function PRINT(exp) {
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return printer._pr_str(exp, true);
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}
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// repl
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var repl_env = new Env();
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var rep = function(str) { return PRINT(EVAL(READ(str), repl_env)); };
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// core.js: defined using javascript
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for (var n in core.ns) { repl_env.set(n, core.ns[n]); }
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repl_env.set('eval', function(ast) {
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return EVAL(ast, repl_env); });
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repl_env.set('*ARGV*', []);
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// core.mal: defined using the language itself
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rep("(def! not (fn* (a) (if a false true)))");
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rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \"\nnil)\")))))");
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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)))))))");
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if (typeof process !== 'undefined' && process.argv.length > 2) {
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repl_env.set(types._symbol('*ARGV*'), process.argv.slice(3));
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rep('(load-file "' + process.argv[2] + '")');
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process.exit(0);
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}
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// repl loop
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if (typeof require !== 'undefined' && require.main === module) {
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// Synchronous node.js commandline mode
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while (true) {
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var line = readline.readline("user> ");
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if (line === null) { break; }
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try {
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if (line) { printer.println(rep(line)); }
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} catch (exc) {
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if (exc instanceof reader.BlankException) { continue }
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if (exc instanceof Error) { console.warn(exc.stack) }
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else { console.warn("Error: " + printer._pr_str(exc, true)) }
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}
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}
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}
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