1 files changed, 49 insertions, 1 deletions

diff --git a/typing.cpp b/typing.cpp
index 9dc94f6..071e582 100644
--- a/typing.cpp
+++ b/typing.cpp
@@ -83,6 +83,54 @@ ASTIf::constrain(TEnv& tenv) const
 }
 
 void
+ASTPrimitive::constrain(TEnv& tenv) const
+{
+	const string n = dynamic_cast<ASTSymbol*>(at(0))->str();
+	enum { ARITHMETIC, BINARY, BITWISE, COMPARISON } type;
+	if (n == "+" || n == "-" || n == "*" || n == "/")
+		type = ARITHMETIC;
+	else if (n == "%")
+		type = BINARY;
+	else if (n == "&" || n == "|" || n == "^")
+		type = BITWISE;
+	else if (n == "=" || n == "!=" || n == ">" || n == ">=" || n == "<" || n == "<=")
+		type = COMPARISON;
+	else
+		throw Error((format("unknown primitive `%1%'") % n).str(), exp.loc);
+
+	FOREACH(const_iterator, p, *this)
+		(*p)->constrain(tenv);
+
+	switch (type) {
+	case ARITHMETIC:
+		if (size() < 3)
+			throw Error((format("`%1%' requires at least 2 arguments") % n).str(), exp.loc);
+		for (size_t i = 1; i < size(); ++i)
+			tenv.constrain(this, tenv.type(at(i)));
+		break;
+	case BINARY:
+		if (size() != 3)
+			throw Error((format("`%1%' requires exactly 2 arguments") % n).str(), exp.loc);
+		tenv.constrain(this, tenv.type(at(1)));
+		tenv.constrain(this, tenv.type(at(2)));
+		break;
+	case BITWISE:
+		if (size() != 3)
+			throw Error((format("`%1%' requires exactly 2 arguments") % n).str(), exp.loc);
+		tenv.constrain(this,  tenv.named("Bool"));
+		tenv.constrain(at(1), tenv.named("Bool"));
+		tenv.constrain(at(2), tenv.named("Bool"));
+		break;
+	case COMPARISON:
+		if (size() != 3)
+			throw Error((format("`%1%' requires exactly 2 arguments") % n).str(), exp.loc);
+		tenv.constrain(this, tenv.named("Bool"));
+		tenv.constrain(at(1), tenv.type(at(2)));
+		break;
+	}
+}
+
+void
 ASTConsCall::constrain(TEnv& tenv) const
 {
 	AType* t = new AType(ASTTuple(tenv.penv.sym("Pair"), 0));
@@ -174,7 +222,7 @@ TEnv::unify(const Constraints& constraints) // TAPL 22.4
 	} else if (t->var() && !s->contains(t)) {
 		substConstraints(cp, t, s);
 		return compose(unify(cp), TSubst(t, s));
-	} else if (s->size() == t->size()) {
+	} else if (s->kind == AType::EXPR && s->kind == t->kind && s->size() == t->size()) {
 		for (size_t i = 0; i < s->size(); ++i) {
 			AType* si = dynamic_cast<AType*>(s->at(i));
 			AType* ti = dynamic_cast<AType*>(t->at(i));