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initial support for nil, make-list

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unfinished, but usable.. still 0 is false in libs and code
This commit is contained in:
VaclavT
2021-03-01 18:26:58 +01:00
parent 46b29fc229
commit 8586a66285
6 changed files with 55 additions and 13 deletions
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37
ml.cpp
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@@ -30,7 +30,6 @@
#define INVALID_ORDER "cannot order expression"
#define BAD_CAST "cannot cast"
#define ATOM_NOT_DEFINED "atom not defined"
#define EVAL_EMPTY_LIST "evaluated empty list"
#define INTERNAL_ERROR "internal virtual machine error"
#define INDEX_OUT_OF_RANGE "index out of range"
#define MALFORMED_PROGRAM "malformed program"
@@ -40,6 +39,7 @@
#define INT_TYPE "int"
#define FLOAT_TYPE "float"
#define UNIT_TYPE "unit"
#define NIL_TYPE "nil"
#define FUNCTION_TYPE "function"
#define ATOM_TYPE "atom"
#define QUOTE_TYPE "quote"
@@ -93,6 +93,12 @@ MlValue MlValue::string(const std::string &s) {
return result;
}
MlValue MlValue::nil() {
MlValue result;
result.type = NIL;
return result;
}
// Construct a lambda function
MlValue::MlValue(const std::vector<MlValue> &params, MlValue ret, MlEnvironment const &env) : type(LAMBDA) {
// We store the params and the result in the list member
@@ -162,7 +168,7 @@ bool MlValue::is_number() const {
// Get the "truthy" boolean value of this value.
bool MlValue::as_bool() const {
return *this != MlValue(0);
return type != NIL && *this != MlValue(0); // TODO remove 0 as false
}
// Get this item's integer value
@@ -281,6 +287,8 @@ bool MlValue::operator==(MlValue other) const {
// The values for quotes are stored in the
// first slot of the list member.
return list[0] == other.list[0];
case NIL:
return other.type == NIL;
default:
return true;
}
@@ -516,6 +524,8 @@ std::string MlValue::get_type_name() {
return FUNCTION_TYPE;
case UNIT:
return UNIT_TYPE;
case NIL:
return NIL_TYPE;
default:
// We don't know the name of this type.
// This isn't the users fault, this is just unhandled.
@@ -553,6 +563,8 @@ std::string MlValue::display() const {
return "<" + str + " at " + to_string(long(stack_data.b)) + ">";
case UNIT:
return "@";
case NIL:
return "nil";
default:
// We don't know how to display whatever type this is.
// This isn't the users fault, this is just unhandled.
@@ -594,6 +606,8 @@ std::string MlValue::debug() const {
return "<" + str + " at " + to_string(long(stack_data.b)) + ">";
case UNIT:
return "@";
case NIL:
return "nil";
default:
// We don't know how to debug whatever type this is.
// This isn't the users fault, this is just unhandled.
@@ -621,8 +635,7 @@ MlError::~MlError() {
}
std::string MlError::description() {
return "error: the expression `" + cause->debug() + "` failed in scope " + to_string(env) + " with message \"" +
msg + "\"";
return "error: the expression `" + cause->debug() + "` failed in scope " + to_string(env) + " with message \"" + msg + "\"";
}
void MlEnvironment::combine(MlEnvironment const &other) {
@@ -657,9 +670,7 @@ MlValue MlValue::apply(std::vector<MlValue> args, MlEnvironment &env) {
// Get the list of parameter atoms
params = list[0].list;
if (params.size() != args.size())
throw MlError(MlValue(args), env, args.size() > params.size() ?
TOO_MANY_ARGS : TOO_FEW_ARGS
);
throw MlError(MlValue(args), env, args.size() > params.size() ? TOO_MANY_ARGS : TOO_FEW_ARGS);
// Get the captured scope from the lambda
e = lambda_scope;
@@ -701,7 +712,7 @@ MlValue MlValue::eval(MlEnvironment &env) {
return env.get(str);
case LIST:
if (list.size() < 1)
throw MlError(*this, env, EVAL_EMPTY_LIST);
return MlValue::nil();
args = std::vector<MlValue>(list.begin() + 1, list.end());
@@ -747,6 +758,7 @@ MlValue parse(std::string &s, int &ptr) {
if (s == "") {
return MlValue();
} else if (s[ptr] == '\'') {
// If this is a quote
ptr++;
@@ -807,6 +819,7 @@ MlValue parse(std::string &s, int &ptr) {
}
return MlValue::string(x);
} else if (s[ptr] == '@') {
ptr++;
skip_whitespace(s, ptr);
@@ -822,7 +835,11 @@ MlValue parse(std::string &s, int &ptr) {
std::string x = s.substr(ptr, n);
ptr += n;
skip_whitespace(s, ptr);
return MlValue::atom(x);
if (x == "nil")
return MlValue::nil();
else
return MlValue::atom(x);
} else {
throw std::runtime_error(MALFORMED_PROGRAM);
}
@@ -1765,7 +1782,7 @@ int main(int argc, const char **argv) {
try {
load_std_lib(env);
// for xcode profiling
// run(read_file_contents("/Users/vaclavt/Development/mlisp/tests/test.lsp"), env);
run(read_file_contents("/Users/vaclavt/Development/mlisp/tests/test.lsp"), env);
if (argc == 1 || (argc == 2 && std::string(argv[1]) == "-i"))
repl(env);