Index: src/ResolvExpr/TypeEnvironment.cc
===================================================================
--- src/ResolvExpr/TypeEnvironment.cc	(revision 4a8f15041541ed05d71e64f45bf5cca3616efdcb)
+++ src/ResolvExpr/TypeEnvironment.cc	(revision cd6a6ffee16b2e0915b5be3211ed86e60fd011e9)
@@ -107,9 +107,13 @@
 
 	void EqvClass::print( std::ostream &os, Indenter indent ) const {
-		if( !deterministic_output ) {
-			os << "( ";
-			std::copy( vars.begin(), vars.end(), std::ostream_iterator< std::string >( os, " " ) );
-			os << ")";
-		}
+		os << "(";
+		bool first = true;
+		for(const auto & var : vars) {
+			if(first) first = false;
+			else os << " ";
+			if( deterministic_output && isUnboundType(var) ) os << "[unbound]";
+			else os << var;
+		}
+		os << ")";
 		if ( type ) {
 			os << " -> ";