mirror of
https://github.com/kanaka/mal.git
synced 2024-09-20 10:07:45 +03:00
321 lines
11 KiB
TypeScript
321 lines
11 KiB
TypeScript
import { readline } from "./node_readline";
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import { Node, MalType, MalString, MalNil, MalList, MalVector, MalHashMap, MalSymbol, MalFunction, isAST, isSeq } from "./types";
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import { Env } from "./env";
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import * as core from "./core";
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import { readStr } from "./reader";
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import { prStr } from "./printer";
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// READ
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function read(str: string): MalType {
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return readStr(str);
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}
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function quasiquote(ast: MalType): MalType {
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if (!isPair(ast)) {
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return new MalList([MalSymbol.get("quote"), ast]);
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}
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if (!isSeq(ast)) {
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throw new Error(`unexpected token type: ${ast.type}, expected: list or vector`);
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}
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const [arg1, arg2] = ast.list;
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if (arg1.type === Node.Symbol && arg1.v === "unquote") {
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return arg2;
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}
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if (isPair(arg1)) {
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if (!isSeq(arg1)) {
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throw new Error(`unexpected token type: ${arg1.type}, expected: list or vector`);
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}
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const [arg11, arg12] = arg1.list;
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if (arg11.type === Node.Symbol && arg11.v === "splice-unquote") {
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return new MalList([
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MalSymbol.get("concat"),
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arg12,
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quasiquote(new MalList(ast.list.slice(1))),
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]);
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}
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}
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return new MalList([
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MalSymbol.get("cons"),
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quasiquote(arg1),
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quasiquote(new MalList(ast.list.slice(1))),
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]);
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function isPair(ast: MalType) {
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if (!isSeq(ast)) {
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return false;
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}
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return 0 < ast.list.length;
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}
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}
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function isMacro(ast: MalType, env: Env): boolean {
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if (!isSeq(ast)) {
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return false;
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}
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const s = ast.list[0];
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if (s.type !== Node.Symbol) {
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return false;
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}
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const foundEnv = env.find(s);
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if (!foundEnv) {
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return false;
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}
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const f = foundEnv.get(s);
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if (f.type !== Node.Function) {
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return false;
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}
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return f.isMacro;
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}
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function macroexpand(ast: MalType, env: Env): MalType {
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while (isMacro(ast, env)) {
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if (!isSeq(ast)) {
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throw new Error(`unexpected token type: ${ast.type}, expected: list or vector`);
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}
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const s = ast.list[0];
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if (s.type !== Node.Symbol) {
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throw new Error(`unexpected token type: ${s.type}, expected: symbol`);
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}
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const f = env.get(s);
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if (f.type !== Node.Function) {
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throw new Error(`unexpected token type: ${f.type}, expected: function`);
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}
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ast = f.func(...ast.list.slice(1));
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}
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return ast;
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}
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function evalAST(ast: MalType, env: Env): MalType {
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switch (ast.type) {
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case Node.Symbol:
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const f = env.get(ast);
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if (!f) {
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throw new Error(`unknown symbol: ${ast.v}`);
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}
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return f;
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case Node.List:
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return new MalList(ast.list.map(ast => evalMal(ast, env)));
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case Node.Vector:
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return new MalVector(ast.list.map(ast => evalMal(ast, env)));
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case Node.HashMap:
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const list: MalType[] = [];
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for (const [key, value] of ast.entries()) {
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list.push(key);
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list.push(evalMal(value, env));
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}
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return new MalHashMap(list);
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default:
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return ast;
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}
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}
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// EVAL
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function evalMal(ast: MalType, env: Env): MalType {
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loop: while (true) {
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if (ast.type !== Node.List) {
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return evalAST(ast, env);
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}
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ast = macroexpand(ast, env);
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if (!isSeq(ast)) {
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return evalAST(ast, env);
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}
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if (ast.list.length === 0) {
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return ast;
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}
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const first = ast.list[0];
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switch (first.type) {
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case Node.Symbol:
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switch (first.v) {
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case "def!": {
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const [, key, value] = ast.list;
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if (key.type !== Node.Symbol) {
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throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
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}
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if (!value) {
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throw new Error(`unexpected syntax`);
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}
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return env.set(key, evalMal(value, env));
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}
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case "let*": {
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env = new Env(env);
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const pairs = ast.list[1];
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if (!isSeq(pairs)) {
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throw new Error(`unexpected token type: ${pairs.type}, expected: list or vector`);
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}
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for (let i = 0; i < pairs.list.length; i += 2) {
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const key = pairs.list[i];
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const value = pairs.list[i + 1];
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if (key.type !== Node.Symbol) {
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throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
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}
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if (!key || !value) {
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throw new Error(`unexpected syntax`);
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}
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env.set(key, evalMal(value, env));
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}
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ast = ast.list[2];
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continue loop;
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}
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case "quote": {
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return ast.list[1];
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}
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case "quasiquote": {
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ast = quasiquote(ast.list[1]);
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continue loop;
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}
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case "defmacro!": {
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const [, key, value] = ast.list;
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if (key.type !== Node.Symbol) {
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throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
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}
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if (!value) {
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throw new Error(`unexpected syntax`);
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}
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const f = evalMal(value, env);
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if (f.type !== Node.Function) {
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throw new Error(`unexpected token type: ${f.type}, expected: function`);
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}
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f.isMacro = true;
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return env.set(key, f);
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}
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case "macroexpand": {
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return macroexpand(ast.list[1], env);
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}
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case "try*": {
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try {
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return evalMal(ast.list[1], env);
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} catch (e) {
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const catchBody = ast.list[2];
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if (!isSeq(catchBody)) {
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throw new Error(`unexpected return type: ${catchBody.type}, expected: list or vector`);
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}
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const catchSymbol = catchBody.list[0];
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if (catchSymbol.type === Node.Symbol && catchSymbol.v === "catch*") {
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const errorSymbol = catchBody.list[1];
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if (errorSymbol.type !== Node.Symbol) {
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throw new Error(`unexpected return type: ${errorSymbol.type}, expected: symbol`);
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}
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if (!isAST(e)) {
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e = new MalString((e as Error).message);
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}
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return evalMal(catchBody.list[2], new Env(env, [errorSymbol], [e]));
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}
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throw e;
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}
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}
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case "do": {
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const list = ast.list.slice(1, -1);
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evalAST(new MalList(list), env);
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ast = ast.list[ast.list.length - 1];
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continue loop;
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}
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case "if": {
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const [, cond, thenExpr, elseExrp] = ast.list;
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const ret = evalMal(cond, env);
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let b = true;
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if (ret.type === Node.Boolean && !ret.v) {
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b = false;
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} else if (ret.type === Node.Nil) {
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b = false;
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}
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if (b) {
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ast = thenExpr;
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} else if (elseExrp) {
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ast = elseExrp;
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} else {
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ast = MalNil.instance;
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}
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continue loop;
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}
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case "fn*": {
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const [, params, bodyAst] = ast.list;
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if (!isSeq(params)) {
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throw new Error(`unexpected return type: ${params.type}, expected: list or vector`);
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}
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const symbols = params.list.map(param => {
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if (param.type !== Node.Symbol) {
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throw new Error(`unexpected return type: ${param.type}, expected: symbol`);
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}
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return param;
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});
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return MalFunction.fromLisp(evalMal, env, symbols, bodyAst);
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}
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}
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}
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const result = evalAST(ast, env);
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if (!isSeq(result)) {
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throw new Error(`unexpected return type: ${result.type}, expected: list or vector`);
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}
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const [f, ...args] = result.list;
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if (f.type !== Node.Function) {
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throw new Error(`unexpected token: ${f.type}, expected: function`);
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}
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if (f.ast) {
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ast = f.ast;
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env = f.newEnv(args);
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continue loop;
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}
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return f.func(...args);
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}
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}
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// PRINT
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function print(exp: MalType): string {
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return prStr(exp);
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}
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const replEnv = new Env();
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function rep(str: string): string {
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return print(evalMal(read(str), replEnv));
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}
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// core.EXT: defined using Racket
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core.ns.forEach((value, key) => {
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replEnv.set(key, value);
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});
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replEnv.set(MalSymbol.get("eval"), MalFunction.fromBootstrap(ast => {
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if (!ast) {
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throw new Error(`undefined argument`);
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}
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return evalMal(ast, replEnv);
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}));
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replEnv.set(MalSymbol.get("*ARGV*"), new MalList([]));
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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) ")")))))`);
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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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rep("(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))");
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if (typeof process !== "undefined" && 2 < process.argv.length) {
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replEnv.set(MalSymbol.get("*ARGV*"), new MalList(process.argv.slice(3).map(s => new MalString(s))));
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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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while (true) {
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const line = readline("user> ");
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if (line == null) {
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break;
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}
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if (line === "") {
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continue;
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}
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try {
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console.log(rep(line));
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} catch (e) {
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const err: Error = e;
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console.error(err.message);
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}
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}
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