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mal - Make a Lisp

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c++11: step 5
2015-03-27 14:00:46 +11:00
#include "MAL.h"
#include "Environment.h"
#include "ReadLine.h"
#include "Types.h"
#include <iostream>
#include <memory>
malValuePtr READ(const String& input);
String PRINT(malValuePtr ast);
static void installFunctions(malEnvPtr env);
static ReadLine s_readLine("~/.mal-history");
Don't pass an env to apply Due to some initial confusion about which env to pass to the eval builtin, I'd been needlessly passing an env to apply all along. No need.
2015-12-14 18:06:50 +11:00
static malEnvPtr replEnv(new malEnv);
c++11: step 5
2015-03-27 14:00:46 +11:00
int main(int argc, char* argv[])
{
String prompt = "user> ";
String input;
installCore(replEnv);
installFunctions(replEnv);
while (s_readLine.get(prompt, input)) {
String out;
try {
out = rep(input, replEnv);
}
catch (malEmptyInputException&) {
continue; // no output
}
catch (String& s) {
out = s;
};
std::cout << out << "\n";
}
return 0;
}
String rep(const String& input, malEnvPtr env)
{
return PRINT(EVAL(READ(input), env));
}
malValuePtr READ(const String& input)
{
return readStr(input);
}
malValuePtr EVAL(malValuePtr ast, malEnvPtr env)
{
Don't pass an env to apply Due to some initial confusion about which env to pass to the eval builtin, I'd been needlessly passing an env to apply all along. No need.
2015-12-14 18:06:50 +11:00
if (!env) {
env = replEnv;
}
c++11: step 5
2015-03-27 14:00:46 +11:00
while (1) {
Merge eval-ast and macro expansion into EVAL, add DEBUG-EVAL 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) .
2022-01-10 00:15:40 +01:00
const malEnvPtr dbgenv = env->find("DEBUG-EVAL");
if (dbgenv && dbgenv->get("DEBUG-EVAL")->isTrue()) {
std::cout << "EVAL: " << PRINT(ast) << "\n";
}
c++11: step 5
2015-03-27 14:00:46 +11:00
const malList* list = DYNAMIC_CAST(malList, ast);
if (!list || (list->count() == 0)) {
return ast->eval(env);
}
// From here on down we are evaluating a non-empty list.
// First handle the special forms.
if (const malSymbol* symbol = DYNAMIC_CAST(malSymbol, list->item(0))) {
String special = symbol->value();
int argCount = list->count() - 1;
if (special == "def!") {
checkArgsIs("def!", 2, argCount);
const malSymbol* id = VALUE_CAST(malSymbol, list->item(1));
return env->set(id->value(), EVAL(list->item(2), env));
}
if (special == "do") {
checkArgsAtLeast("do", 1, argCount);
for (int i = 1; i < argCount; i++) {
EVAL(list->item(i), env);
}
ast = list->item(argCount);
continue; // TCO
}
if (special == "fn*") {
checkArgsIs("fn*", 2, argCount);
const malSequence* bindings =
VALUE_CAST(malSequence, list->item(1));
StringVec params;
for (int i = 0; i < bindings->count(); i++) {
const malSymbol* sym =
VALUE_CAST(malSymbol, bindings->item(i));
params.push_back(sym->value());
}
return mal::lambda(params, list->item(2), env);
}
if (special == "if") {
checkArgsBetween("if", 2, 3, argCount);
bool isTrue = EVAL(list->item(1), env)->isTrue();
if (!isTrue && (argCount == 2)) {
return mal::nilValue();
}
ast = list->item(isTrue ? 2 : 3);
continue; // TCO
}
if (special == "let*") {
checkArgsIs("let*", 2, argCount);
const malSequence* bindings =
VALUE_CAST(malSequence, list->item(1));
int count = checkArgsEven("let*", bindings->count());
malEnvPtr inner(new malEnv(env));
for (int i = 0; i < count; i += 2) {
const malSymbol* var =
VALUE_CAST(malSymbol, bindings->item(i));
inner->set(var->value(), EVAL(bindings->item(i+1), inner));
}
ast = list->item(2);
env = inner;
continue; // TCO
}
}
// Now we're left with the case of a regular list to be evaluated.
std::unique_ptr<malValueVec> items(list->evalItems(env));
malValuePtr op = items->at(0);
if (const malLambda* lambda = DYNAMIC_CAST(malLambda, op)) {
ast = lambda->getBody();
env = lambda->makeEnv(items->begin()+1, items->end());
continue; // TCO
}
else {
Don't pass an env to apply Due to some initial confusion about which env to pass to the eval builtin, I'd been needlessly passing an env to apply all along. No need.
2015-12-14 18:06:50 +11:00
return APPLY(op, items->begin()+1, items->end());
c++11: step 5
2015-03-27 14:00:46 +11:00
}
}
}
String PRINT(malValuePtr ast)
{
return ast->print(true);
}
Don't pass an env to apply Due to some initial confusion about which env to pass to the eval builtin, I'd been needlessly passing an env to apply all along. No need.
2015-12-14 18:06:50 +11:00
malValuePtr APPLY(malValuePtr op, malValueIter argsBegin, malValueIter argsEnd)
c++11: step 5
2015-03-27 14:00:46 +11:00
{
const malApplicable* handler = DYNAMIC_CAST(malApplicable, op);
Split ASSERT into ASSERT and MAL_CHECK/MAL_FAIL * ASSERT is to check for internal errors * MAL_CHECK / MAL_FAIL is to check mal code errors
2015-03-28 22:54:26 +11:00
MAL_CHECK(handler != NULL,
"\"%s\" is not applicable", op->print(true).c_str());
c++11: step 5
2015-03-27 14:00:46 +11:00
Don't pass an env to apply Due to some initial confusion about which env to pass to the eval builtin, I'd been needlessly passing an env to apply all along. No need.
2015-12-14 18:06:50 +11:00
return handler->apply(argsBegin, argsEnd);
c++11: step 5
2015-03-27 14:00:46 +11:00
}
static const char* malFunctionTable[] = {
"(def! not (fn* (cond) (if cond false true)))",
};
static void installFunctions(malEnvPtr env) {
Replace table iterations with new for-loop syntax Didn't even know this existed!
2015-03-28 12:22:01 +11:00
for (auto &function : malFunctionTable) {
rep(function, env);
c++11: step 5
2015-03-27 14:00:46 +11:00
}
}
c++11: step A
2015-03-27 17:24:20 +11:00
// Added to keep the linker happy at step A
malValuePtr readline(const String& prompt)
{
String input;
if (s_readLine.get(prompt, input)) {
return mal::string(input);
}
return mal::nilValue();
}
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