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

module main;

import std.algorithm;
import std.array;
import std.range;
import std.stdio;
import std.string;
import std.c.process;
import env;
import mal_core;
import readline;
import reader;
import printer;
import types;

bool is_pair(MalType ast)
{
    auto lst = cast(MalSequential) ast;
    if (lst is null) return false;
    return lst.elements.length > 0;
}

MalType quasiquote(MalType ast)
{
    if (!is_pair(ast))
    {
        return new MalList([sym_quote, ast]);
    }
    auto ast_seq = verify_cast!MalSequential(ast);
    auto aste = ast_seq.elements;
    if (aste[0] == sym_unquote)
    {
        return aste[1];
    }

    if (is_pair(aste[0]))
    {
        auto ast0_seq = verify_cast!MalSequential(aste[0]);
        if (ast0_seq.elements[0] == sym_splice_unquote)
        {
            return new MalList([new MalSymbol("concat"), ast0_seq.elements[1], quasiquote(new MalList(aste[1..$]))]);
        }
    }

    return new MalList([new MalSymbol("cons"), quasiquote(aste[0]), quasiquote(new MalList(aste[1..$]))]);
}

bool is_macro_call(MalType ast, Env env)
{
    auto lst = cast(MalList) ast;
    if (lst is null) return false;
    if (lst.elements.length == 0) return false;
    auto sym0 = cast(MalSymbol) lst.elements[0];
    if (sym0 is null) return false;
    if (env.find(sym0) is null) return false;
    auto val = env.get(sym0);
    auto val_func = cast(MalFunc) val;
    if (val_func is null) return false;
    return val_func.is_macro;
}

MalType macroexpand(MalType ast, Env env)
{
    while (is_macro_call(ast, env))
    {
        auto ast_list = verify_cast!MalList(ast);
        auto sym0 = verify_cast!MalSymbol(ast_list.elements[0]);
        auto macrofunc = verify_cast!MalFunc(env.get(sym0));
        auto rest = ast_list.elements[1..$];
        auto callenv = new Env(macrofunc.def_env, macrofunc.arg_names, rest);
        ast = EVAL(macrofunc.func_body, callenv);
    }
    return ast;
}

MalType READ(string str)
{
    return read_str(str);
}

MalType eval_ast(MalType ast, Env env)
{
    if (typeid(ast) == typeid(MalSymbol))
    {
        auto sym = verify_cast!MalSymbol(ast);
        return env.get(sym);
    }
    else if (typeid(ast) == typeid(MalList))
    {
        auto lst = verify_cast!MalList(ast);
        auto el = array(lst.elements.map!(e => EVAL(e, env)));
        return new MalList(el);
    }
    else if (typeid(ast) == typeid(MalVector))
    {
        auto lst = verify_cast!MalVector(ast);
        auto el = array(lst.elements.map!(e => EVAL(e, env)));
        return new MalVector(el);
    }
    else if (typeid(ast) == typeid(MalHashmap))
    {
        auto hm = verify_cast!MalHashmap(ast);
        typeof(hm.data) new_data;
        foreach (string k, MalType v; hm.data)
        {
            new_data[k] = EVAL(v, env);
        }
        return new MalHashmap(new_data);
    }
    else
    {
        return ast;
    }
}

MalType EVAL(MalType ast, Env env)
{
    for (;;)
    {
        MalList ast_list = cast(MalList) ast;
        if (ast_list is null)
        {
            return eval_ast(ast, env);
        }

        ast = macroexpand(ast, env);
        ast_list = cast(MalList) ast;
        if (ast_list is null)
        {
            return ast;
        }

        auto aste = ast_list.elements;
        auto a0_sym = cast(MalSymbol) aste[0];
        auto sym_name = a0_sym is null ? "" : a0_sym.name;
        switch (sym_name)
        {
            case "def!":
                auto a1 = verify_cast!MalSymbol(aste[1]);
                return env.set(a1, EVAL(aste[2], env));

            case "let*":
                auto a1 = verify_cast!MalSequential(aste[1]);
                auto let_env = new Env(env);
                foreach (kv; chunks(a1.elements, 2))
                {
                    if (kv.length < 2) throw new Exception("let* requires even number of elements");
                    auto var_name = verify_cast!MalSymbol(kv[0]);
                    let_env.set(var_name, EVAL(kv[1], let_env));
                }
                ast = aste[2];
                env = let_env;
                continue; // TCO

            case "quote":
                return aste[1];

            case "quasiquote":
                ast = quasiquote(aste[1]);
                continue; // TCO

            case "defmacro!":
                auto a1 = verify_cast!MalSymbol(aste[1]);
                auto mac = verify_cast!MalFunc(EVAL(aste[2], env));
                mac.is_macro = true;
                return env.set(a1, mac);

            case "macroexpand":
                return macroexpand(aste[1], env);

            case "do":
                auto all_but_last = new MalList(aste[1..$-1]);
                eval_ast(all_but_last, env);
                ast = aste[$-1];
                continue; // TCO

            case "if":
                auto cond = EVAL(aste[1], env);
                if (cond.is_truthy())
                {
                    ast = aste[2];
                    continue; // TCO
                }
                else
                    if (aste.length > 3)
                    {
                        ast = aste[3];
                        continue; // TCO
                    }
                    else
                    {
                        return mal_nil;
                    }

            case "fn*":
                auto args_list = verify_cast!MalSequential(aste[1]);
                return new MalFunc(args_list.elements, aste[2], env);

            default:
                auto el = verify_cast!MalList(eval_ast(ast, env));
                if (el.elements.length == 0)
                {
                    throw new Exception("Expected a non-empty list");
                }
                auto first = el.elements[0];
                auto rest = el.elements[1..$];
                if (typeid(first) == typeid(MalFunc))
                {
                    auto funcobj = verify_cast!MalFunc(first);
                    auto callenv = new Env(funcobj.def_env, funcobj.arg_names, rest);
                    ast = funcobj.func_body;
                    env = callenv;
                    continue; // TCO
                }
                else if (typeid(first) == typeid(MalBuiltinFunc))
                {
                    auto builtinfuncobj = verify_cast!MalBuiltinFunc(first);
                    return builtinfuncobj.fn(rest);
                }
                else
                {
                    throw new Exception("Expected a function");
                }
        }
    }
}

string PRINT(MalType ast)
{
    return pr_str(ast);
}

MalType re(string str, Env env)
{
    return EVAL(READ(str), env);
}

string rep(string str, Env env)
{
    return PRINT(re(str, env));
}

static MalList create_argv_list(string[] args)
{
    if (args.length <= 2) return new MalList([]);
    return new MalList(array(args[2..$].map!(s => cast(MalType)(new MalString(s)))));
}

void main(string[] args)
{
    Env repl_env = new Env(null);
    foreach (string sym_name, BuiltinStaticFuncType f; core_ns)
    {
        repl_env.set(new MalSymbol(sym_name), new MalBuiltinFunc(f, sym_name));
    }

    BuiltinFuncType eval_func = (a ...) {
        verify_args_count(a, 1);
        return EVAL(a[0], repl_env);
    };
    repl_env.set(new MalSymbol("eval"), new MalBuiltinFunc(eval_func, "eval"));
    repl_env.set(new MalSymbol("*ARGV*"), create_argv_list(args));

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

    if (args.length > 1)
    {
        try
        {
            rep("(load-file \"" ~ args[1] ~ "\")", repl_env);
            return;
        }
        catch (Exception e)
        {
            writeln("Error: ", e.msg);
            std.c.process.exit(1);
        }
    }

    for (;;)
    {
        string line = _readline("user> ");
        if (line is null) break;
        if (line.length == 0) continue;
        try
        {
            writeln(rep(line, repl_env));
        }
        catch (Exception e)
        {
            writeln("Error: ", e.msg);
        }
    }
    writeln("");
}
Commit	Line	Data
f82cb965 DM	1	module main;
	2
	3	import std.algorithm;
	4	import std.array;
	5	import std.range;
	6	import std.stdio;
	7	import std.string;
	8	import std.c.process;
	9	import env;
	10	import mal_core;
	11	import readline;
	12	import reader;
	13	import printer;
	14	import types;
	15
	16	bool is_pair(MalType ast)
	17	{
	18	auto lst = cast(MalSequential) ast;
	19	if (lst is null) return false;
	20	return lst.elements.length > 0;
	21	}
	22
	23	MalType quasiquote(MalType ast)
	24	{
	25	if (!is_pair(ast))
	26	{
	27	return new MalList([sym_quote, ast]);
	28	}
	29	auto ast_seq = verify_cast!MalSequential(ast);
	30	auto aste = ast_seq.elements;
	31	if (aste[0] == sym_unquote)
	32	{
	33	return aste[1];
	34	}
	35
	36	if (is_pair(aste[0]))
	37	{
	38	auto ast0_seq = verify_cast!MalSequential(aste[0]);
	39	if (ast0_seq.elements[0] == sym_splice_unquote)
	40	{
	41	return new MalList([new MalSymbol("concat"), ast0_seq.elements[1], quasiquote(new MalList(aste[1..$]))]);
	42	}
	43	}
	44
	45	return new MalList([new MalSymbol("cons"), quasiquote(aste[0]), quasiquote(new MalList(aste[1..$]))]);
	46	}
	47
	48	bool is_macro_call(MalType ast, Env env)
	49	{
	50	auto lst = cast(MalList) ast;
	51	if (lst is null) return false;
	52	if (lst.elements.length == 0) return false;
	53	auto sym0 = cast(MalSymbol) lst.elements[0];
	54	if (sym0 is null) return false;
	55	if (env.find(sym0) is null) return false;
	56	auto val = env.get(sym0);
	57	auto val_func = cast(MalFunc) val;
	58	if (val_func is null) return false;
	59	return val_func.is_macro;
	60	}
	61
	62	MalType macroexpand(MalType ast, Env env)
	63	{
	64	while (is_macro_call(ast, env))
65	{
66	auto ast_list = verify_cast!MalList(ast);
67	auto sym0 = verify_cast!MalSymbol(ast_list.elements[0]);
68	auto macrofunc = verify_cast!MalFunc(env.get(sym0));
69	auto rest = ast_list.elements[1..$];
70	auto callenv = new Env(macrofunc.def_env, macrofunc.arg_names, rest);
71	ast = EVAL(macrofunc.func_body, callenv);
72	}
73	return ast;
74	}
75
76	MalType READ(string str)
77	{
78	return read_str(str);
79	}
80
81	MalType eval_ast(MalType ast, Env env)
82	{
83	if (typeid(ast) == typeid(MalSymbol))
84	{
85	auto sym = verify_cast!MalSymbol(ast);
86	return env.get(sym);
87	}
88	else if (typeid(ast) == typeid(MalList))
89	{
90	auto lst = verify_cast!MalList(ast);
91	auto el = array(lst.elements.map!(e => EVAL(e, env)));
92	return new MalList(el);
93	}
94	else if (typeid(ast) == typeid(MalVector))
95	{
96	auto lst = verify_cast!MalVector(ast);
97	auto el = array(lst.elements.map!(e => EVAL(e, env)));
98	return new MalVector(el);
99	}
100	else if (typeid(ast) == typeid(MalHashmap))
101	{
102	auto hm = verify_cast!MalHashmap(ast);
103	typeof(hm.data) new_data;
104	foreach (string k, MalType v; hm.data)
105	{
106	new_data[k] = EVAL(v, env);
107	}
108	return new MalHashmap(new_data);
109	}
110	else
111	{
112	return ast;
113	}
114	}
115
116	MalType EVAL(MalType ast, Env env)
117	{
118	for (;;)
119	{
120	MalList ast_list = cast(MalList) ast;
121	if (ast_list is null)
122	{
123	return eval_ast(ast, env);
124	}
125
126	ast = macroexpand(ast, env);
127	ast_list = cast(MalList) ast;
128	if (ast_list is null)
129	{
130	return ast;
131	}
132
133	auto aste = ast_list.elements;
134	auto a0_sym = cast(MalSymbol) aste[0];
135	auto sym_name = a0_sym is null ? "" : a0_sym.name;
136	switch (sym_name)
137	{
138	case "def!":
139	auto a1 = verify_cast!MalSymbol(aste[1]);
140	return env.set(a1, EVAL(aste[2], env));
141
142	case "let*":
143	auto a1 = verify_cast!MalSequential(aste[1]);
144	auto let_env = new Env(env);
145	foreach (kv; chunks(a1.elements, 2))
146	{
147	if (kv.length < 2) throw new Exception("let* requires even number of elements");
148	auto var_name = verify_cast!MalSymbol(kv[0]);
149	let_env.set(var_name, EVAL(kv[1], let_env));
150	}
151	ast = aste[2];
152	env = let_env;
153	continue; // TCO
154
155	case "quote":
156	return aste[1];
157
158	case "quasiquote":
159	ast = quasiquote(aste[1]);
160	continue; // TCO
161
162	case "defmacro!":
163	auto a1 = verify_cast!MalSymbol(aste[1]);
164	auto mac = verify_cast!MalFunc(EVAL(aste[2], env));
165	mac.is_macro = true;
166	return env.set(a1, mac);
167
168	case "macroexpand":
169	return macroexpand(aste[1], env);
170
171	case "do":
172	auto all_but_last = new MalList(aste[1..$-1]);
173	eval_ast(all_but_last, env);
174	ast = aste[$-1];
175	continue; // TCO
176
177	case "if":
178	auto cond = EVAL(aste[1], env);
179	if (cond.is_truthy())
180	{
181	ast = aste[2];
182	continue; // TCO
183	}
184	else
185	if (aste.length > 3)
186	{
187	ast = aste[3];
188	continue; // TCO
189	}
190	else
191	{
192	return mal_nil;
193	}
194
195	case "fn*":
196	auto args_list = verify_cast!MalSequential(aste[1]);
197	return new MalFunc(args_list.elements, aste[2], env);
198
199	default:
200	auto el = verify_cast!MalList(eval_ast(ast, env));
201	if (el.elements.length == 0)
202	{
203	throw new Exception("Expected a non-empty list");
204	}
205	auto first = el.elements[0];
206	auto rest = el.elements[1..$];
207	if (typeid(first) == typeid(MalFunc))
208	{
209	auto funcobj = verify_cast!MalFunc(first);
210	auto callenv = new Env(funcobj.def_env, funcobj.arg_names, rest);
211	ast = funcobj.func_body;
212	env = callenv;
213	continue; // TCO
214	}
215	else if (typeid(first) == typeid(MalBuiltinFunc))
216	{
217	auto builtinfuncobj = verify_cast!MalBuiltinFunc(first);
218	return builtinfuncobj.fn(rest);
219	}
220	else
221	{
222	throw new Exception("Expected a function");
223	}
224	}
225	}
226	}
227
228	string PRINT(MalType ast)
229	{
230	return pr_str(ast);
231	}
232
233	MalType re(string str, Env env)
234	{
235	return EVAL(READ(str), env);
236	}
237
238	string rep(string str, Env env)
239	{
240	return PRINT(re(str, env));
241	}
242
243	static MalList create_argv_list(string[] args)
244	{
245	if (args.length <= 2) return new MalList([]);
246	return new MalList(array(args[2..$].map!(s => cast(MalType)(new MalString(s)))));
247	}
248
249	void main(string[] args)
250	{
251	Env repl_env = new Env(null);
252	foreach (string sym_name, BuiltinStaticFuncType f; core_ns)
253	{
254	repl_env.set(new MalSymbol(sym_name), new MalBuiltinFunc(f, sym_name));
255	}
256
257	BuiltinFuncType eval_func = (a ...) {
258	verify_args_count(a, 1);
259	return EVAL(a[0], repl_env);
260	};
261	repl_env.set(new MalSymbol("eval"), new MalBuiltinFunc(eval_func, "eval"));
262	repl_env.set(new MalSymbol("ARGV"), create_argv_list(args));
263
264	// core.mal: defined using the language itself
265	re("(def! not (fn* (a) (if a false true)))", repl_env);
266	re("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))", repl_env);
267	re("(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)))))))", repl_env);
268	re("(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))))))))", repl_env);
269
270	if (args.length > 1)
271	{
272	try
273	{
274	rep("(load-file \"" ~ args[1] ~ "\")", repl_env);
275	return;
276	}
277	catch (Exception e)
278	{
279	writeln("Error: ", e.msg);
280	std.c.process.exit(1);
281	}
282	}
283
284	for (;;)
285	{
286	string line = _readline("user> ");
287	if (line is null) break;
288	if (line.length == 0) continue;
289	try
290	{
291	writeln(rep(line, repl_env));
292	}
293	catch (Exception e)
294	{
295	writeln("Error: ", e.msg);
296	}
297	}
298	writeln("");
299	}