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#include "ast.hpp"
std::string op_name(binop op) {
switch(op) {
case PLUS: return "+";
case MINUS: return "-";
case TIMES: return "*";
case DIVIDE: return "/";
}
throw 0;
}
type_ptr ast_int::typecheck(type_mgr& mgr, const type_env& env) const {
return type_ptr(new type_base("Int"));
}
type_ptr ast_lid::typecheck(type_mgr& mgr, const type_env& env) const {
return env.lookup(id);
}
type_ptr ast_uid::typecheck(type_mgr& mgr, const type_env& env) const {
return env.lookup(id);
}
type_ptr ast_binop::typecheck(type_mgr& mgr, const type_env& env) const {
type_ptr ltype = left->typecheck(mgr, env);
type_ptr rtype = right->typecheck(mgr, env);
type_ptr ftype = env.lookup(op_name(op));
if(!ftype) throw 0;
type_ptr return_type = mgr.new_type();
type_ptr arrow_one = type_ptr(new type_arr(rtype, return_type));
type_ptr arrow_two = type_ptr(new type_arr(ltype, arrow_one));
mgr.unify(arrow_two, ftype);
return return_type;
}
type_ptr ast_app::typecheck(type_mgr& mgr, const type_env& env) const {
type_ptr ltype = left->typecheck(mgr, env);
type_ptr rtype = right->typecheck(mgr, env);
type_ptr return_type = mgr.new_type();
type_ptr arrow = type_ptr(new type_arr(rtype, return_type));
mgr.unify(arrow, ltype);
return return_type;
}
type_ptr ast_case::typecheck(type_mgr& mgr, const type_env& env) const {
type_ptr case_type = of->typecheck(mgr, env);
type_ptr branch_type = mgr.new_type();
for(auto& branch : branches) {
type_env new_env = env.scope();
branch->pat->match(case_type, mgr, new_env);
type_ptr curr_branch_type = branch->expr->typecheck(mgr, new_env);
mgr.unify(branch_type, curr_branch_type);
}
return branch_type;
}
void pattern_var::match(type_ptr t, type_mgr& mgr, type_env& env) const {
env.bind(var, t);
}
void pattern_constr::match(type_ptr t, type_mgr& mgr, type_env& env) const {
type_ptr constructor_type = env.lookup(constr);
if(!constructor_type) throw 0;
for(int i = 0; i < params.size(); i++) {
type_arr* arr = dynamic_cast<type_arr*>(constructor_type.get());
if(!arr) throw 0;
env.bind(params[i], arr->left);
constructor_type = arr->right;
}
mgr.unify(t, constructor_type);
type_base* result_type = dynamic_cast<type_base*>(constructor_type.get());
if(!result_type) throw 0;
}