[jackhill/mal.git] / ts / step8_macros.ts

import { readline } from "./node_readline";

import { Node, MalType, MalString, MalNil, MalList, MalVector, MalHashMap, MalSymbol, MalFunction, isSeq } from "./types";
import { Env } from "./env";
import * as core from "./core";
import { readStr } from "./reader";
import { prStr } from "./printer";

// READ
function read(str: string): MalType {
    return readStr(str);
}

function quasiquote(ast: MalType): MalType {
    if (!isPair(ast)) {
        return new MalList([MalSymbol.get("quote"), ast]);
    }
    if (!isSeq(ast)) {
        throw new Error(`unexpected token type: ${ast.type}, expected: list or vector`);
    }
    const [arg1, arg2] = ast.list;
    if (arg1.type === Node.Symbol && arg1.v === "unquote") {
        return arg2;
    }
    if (isPair(arg1)) {
        if (!isSeq(arg1)) {
            throw new Error(`unexpected token type: ${arg1.type}, expected: list or vector`);
        }
        const [arg11, arg12] = arg1.list;
        if (arg11.type === Node.Symbol && arg11.v === "splice-unquote") {
            return new MalList([
                MalSymbol.get("concat"),
                arg12,
                quasiquote(new MalList(ast.list.slice(1))),
            ]);
        }
    }

    return new MalList([
        MalSymbol.get("cons"),
        quasiquote(arg1),
        quasiquote(new MalList(ast.list.slice(1))),
    ]);

    function isPair(ast: MalType) {
        if (!isSeq(ast)) {
            return false;
        }

        return 0 < ast.list.length;
    }
}

function isMacro(ast: MalType, env: Env): boolean {
    if (!isSeq(ast)) {
        return false;
    }
    const s = ast.list[0];
    if (s.type !== Node.Symbol) {
        return false;
    }
    const foundEnv = env.find(s);
    if (!foundEnv) {
        return false;
    }

    const f = foundEnv.get(s);
    if (f.type !== Node.Function) {
        return false;
    }

    return f.isMacro;
}

function macroexpand(ast: MalType, env: Env): MalType {
    while (isMacro(ast, env)) {
        if (!isSeq(ast)) {
            throw new Error(`unexpected token type: ${ast.type}, expected: list or vector`);
        }
        const s = ast.list[0];
        if (s.type !== Node.Symbol) {
            throw new Error(`unexpected token type: ${s.type}, expected: symbol`);
        }
        const f = env.get(s);
        if (f.type !== Node.Function) {
            throw new Error(`unexpected token type: ${f.type}, expected: function`);
        }
        ast = f.func(...ast.list.slice(1));
    }

    return ast;
}

function evalAST(ast: MalType, env: Env): MalType {
    switch (ast.type) {
        case Node.Symbol:
            const f = env.get(ast);
            if (!f) {
                throw new Error(`unknown symbol: ${ast.v}`);
            }
            return f;
        case Node.List:
            return new MalList(ast.list.map(ast => evalMal(ast, env)));
        case Node.Vector:
            return new MalVector(ast.list.map(ast => evalMal(ast, env)));
        case Node.HashMap:
            const list: MalType[] = [];
            for (const [key, value] of ast.entries()) {
                list.push(key);
                list.push(evalMal(value, env));
            }
            return new MalHashMap(list);
        default:
            return ast;
    }
}

// EVAL
function evalMal(ast: MalType, env: Env): MalType {
    loop: while (true) {
        if (ast.type !== Node.List) {
            return evalAST(ast, env);
        }

        ast = macroexpand(ast, env);
        if (!isSeq(ast)) {
            return evalAST(ast, env);
        }

        if (ast.list.length === 0) {
            return ast;
        }
        const first = ast.list[0];
        switch (first.type) {
            case Node.Symbol:
                switch (first.v) {
                    case "def!": {
                        const [, key, value] = ast.list;
                        if (key.type !== Node.Symbol) {
                            throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
                        }
                        if (!value) {
                            throw new Error(`unexpected syntax`);
                        }
                        return env.set(key, evalMal(value, env));
                    }
                    case "let*": {
                        env = new Env(env);
                        const pairs = ast.list[1];
                        if (!isSeq(pairs)) {
                            throw new Error(`unexpected token type: ${pairs.type}, expected: list or vector`);
                        }
                        for (let i = 0; i < pairs.list.length; i += 2) {
                            const key = pairs.list[i];
                            const value = pairs.list[i + 1];
                            if (key.type !== Node.Symbol) {
                                throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
                            }
                            if (!key || !value) {
                                throw new Error(`unexpected syntax`);
                            }

                            env.set(key, evalMal(value, env));
                        }
                        ast = ast.list[2];
                        continue loop;
                    }
                    case "quote": {
                        return ast.list[1];
                    }
                    case "quasiquote": {
                        ast = quasiquote(ast.list[1]);
                        continue loop;
                    }
                    case "defmacro!": {
                        const [, key, value] = ast.list;
                        if (key.type !== Node.Symbol) {
                            throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
                        }
                        if (!value) {
                            throw new Error(`unexpected syntax`);
                        }
                        const f = evalMal(value, env);
                        if (f.type !== Node.Function) {
                            throw new Error(`unexpected token type: ${f.type}, expected: function`);
                        }
                        f.isMacro = true;
                        return env.set(key, f);
                    }
                    case "macroexpand": {
                        return macroexpand(ast.list[1], env);
                    }
                    case "do": {
                        const list = ast.list.slice(1, -1);
                        evalAST(new MalList(list), env);
                        ast = ast.list[ast.list.length - 1];
                        continue loop;
                    }
                    case "if": {
                        const [, cond, thenExpr, elseExrp] = ast.list;
                        const ret = evalMal(cond, env);
                        let b = true;
                        if (ret.type === Node.Boolean && !ret.v) {
                            b = false;
                        } else if (ret.type === Node.Nil) {
                            b = false;
                        }
                        if (b) {
                            ast = thenExpr;
                        } else if (elseExrp) {
                            ast = elseExrp;
                        } else {
                            ast = MalNil.instance;
                        }
                        continue loop;
                    }
                    case "fn*": {
                        const [, params, bodyAst] = ast.list;
                        if (!isSeq(params)) {
                            throw new Error(`unexpected return type: ${params.type}, expected: list or vector`);
                        }
                        const symbols = params.list.map(param => {
                            if (param.type !== Node.Symbol) {
                                throw new Error(`unexpected return type: ${param.type}, expected: symbol`);
                            }
                            return param;
                        });
                        return MalFunction.fromLisp(evalMal, env, symbols, bodyAst);
                    }
                }
        }
        const result = evalAST(ast, env);
        if (!isSeq(result)) {
            throw new Error(`unexpected return type: ${result.type}, expected: list or vector`);
        }
        const [f, ...args] = result.list;
        if (f.type !== Node.Function) {
            throw new Error(`unexpected token: ${f.type}, expected: function`);
        }
        if (f.ast) {
            ast = f.ast;
            env = f.newEnv(args);
            continue loop;
        }

        return f.func(...args);
    }
}

// PRINT
function print(exp: MalType): string {
    return prStr(exp);
}

const replEnv = new Env();
function rep(str: string): string {
    return print(evalMal(read(str), replEnv));
}

// core.EXT: defined using Racket
core.ns.forEach((value, key) => {
    replEnv.set(key, value);
});
replEnv.set(MalSymbol.get("eval"), MalFunction.fromBootstrap(ast => {
    if (!ast) {
        throw new Error(`undefined argument`);
    }
    return evalMal(ast, replEnv);
}));
replEnv.set(MalSymbol.get("*ARGV*"), new MalList([]));

// core.mal: defined using the language itself
rep("(def! not (fn* (a) (if a false true)))");
rep(`(def! load-file (fn* (f) (eval (read-string (str "(do " (slurp f) ")")))))`);
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)))))))`);
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))))))))");

if (typeof process !== "undefined" && 2 < process.argv.length) {
    replEnv.set(MalSymbol.get("*ARGV*"), new MalList(process.argv.slice(3).map(s => new MalString(s))));
    rep(`(load-file "${process.argv[2]}")`);
    process.exit(0);
}

while (true) {
    const line = readline("user> ");
    if (line == null) {
        break;
    }
    if (line === "") {
        continue;
    }
    try {
        console.log(rep(line));
    } catch (e) {
        const err: Error = e;
        console.error(err.message);
    }
}
Commit	Line	Data
e21a85a3	1	import { readline } from "./node_readline";
e21a85a3	2
6071876f	3	import { Node, MalType, MalString, MalNil, MalList, MalVector, MalHashMap, MalSymbol, MalFunction, isSeq } from "./types";
e21a85a3	4	import { Env } from "./env";
	5	import * as core from "./core";
	6	import { readStr } from "./reader";
	7	import { prStr } from "./printer";
	8
9c92462f	9	// READ
e21a85a3	10	function read(str: string): MalType {
	11	return readStr(str);
	12	}
	13
	14	function quasiquote(ast: MalType): MalType {
	15	if (!isPair(ast)) {
	16	return new MalList([MalSymbol.get("quote"), ast]);
	17	}
92bf0530	18	if (!isSeq(ast)) {
e21a85a3	19	throw new Error(`unexpected token type: ${ast.type}, expected: list or vector`);
	20	}
	21	const [arg1, arg2] = ast.list;
5bb7479d	22	if (arg1.type === Node.Symbol && arg1.v === "unquote") {
e21a85a3	23	return arg2;
	24	}
	25	if (isPair(arg1)) {
92bf0530	26	if (!isSeq(arg1)) {
e21a85a3	27	throw new Error(`unexpected token type: ${arg1.type}, expected: list or vector`);
	28	}
	29	const [arg11, arg12] = arg1.list;
5bb7479d	30	if (arg11.type === Node.Symbol && arg11.v === "splice-unquote") {
e21a85a3	31	return new MalList([
	32	MalSymbol.get("concat"),
	33	arg12,
	34	quasiquote(new MalList(ast.list.slice(1))),
	35	]);
	36	}
	37	}
	38
	39	return new MalList([
	40	MalSymbol.get("cons"),
	41	quasiquote(arg1),
	42	quasiquote(new MalList(ast.list.slice(1))),
	43	]);
	44
	45	function isPair(ast: MalType) {
92bf0530	46	if (!isSeq(ast)) {
e21a85a3	47	return false;
	48	}
	49
	50	return 0 < ast.list.length;
	51	}
	52	}
	53
9c92462f	54	function isMacro(ast: MalType, env: Env): boolean {
92bf0530	55	if (!isSeq(ast)) {
e21a85a3	56	return false;
	57	}
	58	const s = ast.list[0];
5bb7479d	59	if (s.type !== Node.Symbol) {
e21a85a3	60	return false;
	61	}
	62	const foundEnv = env.find(s);
	63	if (!foundEnv) {
	64	return false;
	65	}
	66
	67	const f = foundEnv.get(s);
5bb7479d	68	if (f.type !== Node.Function) {
e21a85a3	69	return false;
	70	}
	71
	72	return f.isMacro;
	73	}
	74
	75	function macroexpand(ast: MalType, env: Env): MalType {
9c92462f	76	while (isMacro(ast, env)) {
92bf0530	77	if (!isSeq(ast)) {
e21a85a3	78	throw new Error(`unexpected token type: ${ast.type}, expected: list or vector`);
	79	}
	80	const s = ast.list[0];
5bb7479d	81	if (s.type !== Node.Symbol) {
e21a85a3	82	throw new Error(`unexpected token type: ${s.type}, expected: symbol`);
	83	}
	84	const f = env.get(s);
5bb7479d	85	if (f.type !== Node.Function) {
e21a85a3	86	throw new Error(`unexpected token type: ${f.type}, expected: function`);
	87	}
	88	ast = f.func(...ast.list.slice(1));
	89	}
	90
	91	return ast;
	92	}
	93
	94	function evalAST(ast: MalType, env: Env): MalType {
	95	switch (ast.type) {
5bb7479d	96	case Node.Symbol:
e21a85a3	97	const f = env.get(ast);
	98	if (!f) {
	99	throw new Error(`unknown symbol: ${ast.v}`);
	100	}
	101	return f;
5bb7479d	102	case Node.List:
9c92462f	103	return new MalList(ast.list.map(ast => evalMal(ast, env)));
5bb7479d	104	case Node.Vector:
9c92462f	105	return new MalVector(ast.list.map(ast => evalMal(ast, env)));
5bb7479d	106	case Node.HashMap:
e21a85a3	107	const list: MalType[] = [];
10f8aa84	108	for (const [key, value] of ast.entries()) {
e21a85a3	109	list.push(key);
9c92462f	110	list.push(evalMal(value, env));
e21a85a3	111	}
	112	return new MalHashMap(list);
	113	default:
	114	return ast;
	115	}
	116	}
	117
9c92462f	118	// EVAL
9c92462f	119	function evalMal(ast: MalType, env: Env): MalType {
e21a85a3	120	loop: while (true) {
5bb7479d	121	if (ast.type !== Node.List) {
e21a85a3	122	return evalAST(ast, env);
	123	}
	124
	125	ast = macroexpand(ast, env);
5bb7479d	126	if (!isSeq(ast)) {
e21a85a3	127	return evalAST(ast, env);
	128	}
	129
	130	if (ast.list.length === 0) {
	131	return ast;
	132	}
	133	const first = ast.list[0];
	134	switch (first.type) {
5bb7479d	135	case Node.Symbol:
e21a85a3	136	switch (first.v) {
	137	case "def!": {
	138	const [, key, value] = ast.list;
5bb7479d	139	if (key.type !== Node.Symbol) {
e21a85a3	140	throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
	141	}
	142	if (!value) {
	143	throw new Error(`unexpected syntax`);
	144	}
677a1c9d	145	return env.set(key, evalMal(value, env));
e21a85a3	146	}
	147	case "let*": {
	148	env = new Env(env);
	149	const pairs = ast.list[1];
92bf0530	150	if (!isSeq(pairs)) {
e21a85a3	151	throw new Error(`unexpected token type: ${pairs.type}, expected: list or vector`);
	152	}
	153	for (let i = 0; i < pairs.list.length; i += 2) {
	154	const key = pairs.list[i];
	155	const value = pairs.list[i + 1];
5bb7479d	156	if (key.type !== Node.Symbol) {
e21a85a3	157	throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
	158	}
	159	if (!key \|\| !value) {
	160	throw new Error(`unexpected syntax`);
	161	}
	162
9c92462f	163	env.set(key, evalMal(value, env));
e21a85a3	164	}
	165	ast = ast.list[2];
	166	continue loop;
	167	}
	168	case "quote": {
	169	return ast.list[1];
	170	}
	171	case "quasiquote": {
	172	ast = quasiquote(ast.list[1]);
	173	continue loop;
	174	}
	175	case "defmacro!": {
	176	const [, key, value] = ast.list;
5bb7479d	177	if (key.type !== Node.Symbol) {
e21a85a3	178	throw new Error(`unexpected token type: ${key.type}, expected: symbol`);
	179	}
	180	if (!value) {
	181	throw new Error(`unexpected syntax`);
	182	}
9c92462f	183	const f = evalMal(value, env);
5bb7479d	184	if (f.type !== Node.Function) {
e21a85a3	185	throw new Error(`unexpected token type: ${f.type}, expected: function`);
	186	}
	187	f.isMacro = true;
	188	return env.set(key, f);
	189	}
	190	case "macroexpand": {
	191	return macroexpand(ast.list[1], env);
	192	}
	193	case "do": {
bbddf168	194	const list = ast.list.slice(1, -1);
	195	evalAST(new MalList(list), env);
	196	ast = ast.list[ast.list.length - 1];
e21a85a3	197	continue loop;
	198	}
	199	case "if": {
	200	const [, cond, thenExpr, elseExrp] = ast.list;
9c92462f	201	const ret = evalMal(cond, env);
e21a85a3	202	let b = true;
5bb7479d	203	if (ret.type === Node.Boolean && !ret.v) {
e21a85a3	204	b = false;
6071876f	205	} else if (ret.type === Node.Nil) {
e21a85a3	206	b = false;
	207	}
	208	if (b) {
	209	ast = thenExpr;
	210	} else if (elseExrp) {
	211	ast = elseExrp;
	212	} else {
6071876f	213	ast = MalNil.instance;
e21a85a3	214	}
	215	continue loop;
	216	}
	217	case "fn*": {
	218	const [, params, bodyAst] = ast.list;
92bf0530	219	if (!isSeq(params)) {
e21a85a3	220	throw new Error(`unexpected return type: ${params.type}, expected: list or vector`);
	221	}
	222	const symbols = params.list.map(param => {
5bb7479d	223	if (param.type !== Node.Symbol) {
e21a85a3	224	throw new Error(`unexpected return type: ${param.type}, expected: symbol`);
	225	}
	226	return param;
	227	});
9c92462f	228	return MalFunction.fromLisp(evalMal, env, symbols, bodyAst);
e21a85a3	229	}
	230	}
	231	}
	232	const result = evalAST(ast, env);
92bf0530	233	if (!isSeq(result)) {
e21a85a3	234	throw new Error(`unexpected return type: ${result.type}, expected: list or vector`);
	235	}
	236	const [f, ...args] = result.list;
5bb7479d	237	if (f.type !== Node.Function) {
e21a85a3	238	throw new Error(`unexpected token: ${f.type}, expected: function`);
	239	}
	240	if (f.ast) {
	241	ast = f.ast;
	242	env = f.newEnv(args);
	243	continue loop;
	244	}
	245
	246	return f.func(...args);
	247	}
	248	}
	249
9c92462f	250	// PRINT
e21a85a3	251	function print(exp: MalType): string {
	252	return prStr(exp);
	253	}
	254
	255	const replEnv = new Env();
9c92462f	256	function rep(str: string): string {
	257	return print(evalMal(read(str), replEnv));
	258	}
	259
	260	// core.EXT: defined using Racket
eb7a2bbd	261	core.ns.forEach((value, key) => {
e21a85a3	262	replEnv.set(key, value);
eb7a2bbd	263	});
e21a85a3	264	replEnv.set(MalSymbol.get("eval"), MalFunction.fromBootstrap(ast => {
	265	if (!ast) {
	266	throw new Error(`undefined argument`);
	267	}
9c92462f	268	return evalMal(ast, replEnv);
e21a85a3	269	}));
e21a85a3	270	replEnv.set(MalSymbol.get("ARGV"), new MalList([]));
	271
	272	// core.mal: defined using the language itself
	273	rep("(def! not (fn* (a) (if a false true)))");
	274	rep(`(def! load-file (fn* (f) (eval (read-string (str "(do " (slurp f) ")")))))`);
	275	rep(`(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw "odd number of forms to cond")) (cons 'cond (rest (rest xs)))))))`);
677a1c9d	276	rep("(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))");
e21a85a3	277
	278	if (typeof process !== "undefined" && 2 < process.argv.length) {
	279	replEnv.set(MalSymbol.get("ARGV"), new MalList(process.argv.slice(3).map(s => new MalString(s))));
	280	rep(`(load-file "${process.argv[2]}")`);
	281	process.exit(0);
	282	}
	283
e21a85a3	284	while (true) {
	285	const line = readline("user> ");
	286	if (line == null) {
	287	break;
	288	}
	289	if (line === "") {
	290	continue;
	291	}
	292	try {
	293	console.log(rep(line));
	294	} catch (e) {
	295	const err: Error = e;
	296	console.error(err.message);
	297	}
	298	}