EnvPtr Env::InitializeGlobalEnv()
{
EnvPtr global = make_shared<Env>();
global->AddProcedure("+", [] (const List& lst) -> LispData {
auto summator = [] (const LispData& a, const DataPtr b) -> LispData {
if (a.GetType() == integer_type && b->GetType() == integer_type) {
return LispData(a.GetInt() + b->GetInt());
}
else {
return LispData(a.GetFloat() + b->GetFloat());
}
};
return accumulate(begin(lst), end(lst), LispData(0L), summator);
});
global->AddProcedure("-", [] (const List& lst) -> LispData {
if (lst.size() != 2) {
throw WrongArity("-");
}
LispData a = *lst.front();
LispData b = *lst.back();
if (a.GetType() == integer_type && b.GetType() == integer_type) {
return LispData(a.GetInt() - b.GetInt());
}
else {
return LispData(a.GetFloat() - b.GetFloat());
}
});
global->AddProcedure("*", [] (const List& lst) -> LispData {
auto multiplicator = [] (const LispData& a, const DataPtr b) -> LispData {
if (a.GetType() == integer_type && b->GetType() == integer_type) {
return LispData(a.GetInt() * b->GetInt());
}
else {
return LispData(a.GetFloat() * b->GetFloat());
}
};
return accumulate(begin(lst), end(lst), LispData(1), multiplicator);
});
global->AddProcedure("/", [] (const List& lst) -> LispData {
if (lst.size() != 2) {
throw WrongArity("/");
}
LispData a = *lst.front();
LispData b = *lst.back();
if (fabs(b.GetFloat()) < 1e-15) {
throw runtime_error("Zero division");
}
if (a.GetType() == integer_type && b.GetType() == integer_type) {
return LispData(a.GetInt() / b.GetInt());
}
else {
return LispData(a.GetFloat() / b.GetFloat());
}
});
global->AddProcedure("=", [] (const List& lst) -> LispData {
if (lst.size() != 2) {
throw WrongArity("=");
}
LispData a = *lst.front();
LispData b = *lst.back();
return LispData(a.GetFloat() == b.GetFloat());
});
global->AddProcedure("cons", [] (const List& lst) -> LispData {
if (lst.size() != 2) {
throw WrongArity("cons");
}
return LispData(lst);
});
global->AddProcedure("car", [] (const List& lst) -> LispData {
if (lst.size() != 1) {
throw WrongArity("car");
}
if (lst.front()->GetType() != list_type) {
throw runtime_error("Not pair type given to 'car'.");
}
return LispData(*lst.front()->GetListRef()->front());
});
global->AddProcedure("cdr", [] (const List& lst) -> LispData {
if (lst.size() != 1) {
throw WrongArity("cdr");
}
auto pair = lst.front();
if (pair->GetType() != list_type || pair->GetListRef()->size() != 2) {
throw runtime_error("Not pair type given to 'cdr'.");
}
return LispData(*pair->GetListRef()->back());
});
global->AddProcedure("null?", [] (const List& lst) -> LispData {
if (lst.size() != 1) {
throw WrongArity("null?");
}
auto pair = lst.front();
if (pair->GetType() != list_type) {
throw runtime_error("Not pair type given to 'null?'.");
}
return LispData(pair->GetListRef()->empty());
});
(*global)["nil"] = LispData(List());
global->AddProcedure("exit", [] (const List&) -> LispData {
exit(0);
});
return global;
}
