Added a FlatTypes() method for easier access for some logic-related work

functionType.go

@@ -81,3 +81,26 @@ func (t *FunctionType) Ret(recursive bool) Type {
 
 	return t.b
 }
+
+// FlatTypes returns the types in FunctionTypes as a flat slice of types. This allows for easier iteration in some applications
+func (t *FunctionType) FlatTypes() Types {
+	retVal := BorrowTypes(8) // start with 8. Can always grow
+	retVal = retVal[:0]
+
+	if a, ok := t.a.(*FunctionType); ok {
+		ft := a.FlatTypes()
+		retVal = append(retVal, ft...)
+		ReturnTypes(ft)
+	} else {
+		retVal = append(retVal, t.a)
+	}
+
+	if b, ok := t.b.(*FunctionType); ok {
+		ft := b.FlatTypes()
+		retVal = append(retVal, ft...)
+		ReturnTypes(ft)
+	} else {
+		retVal = append(retVal, t.b)
+	}
+	return retVal
+}

functionType_test.go

@@ -75,3 +75,15 @@ var fnApplyTests = []struct {
 	// (a -> b) -> c
 	{NewFnType(NewFnType(TypeVariable('a'), TypeVariable('b')), TypeVariable('a')), mSubs{'a': proton, 'b': neutron}, NewFnType(NewFnType(proton, neutron), proton)},
 }
+
+func TestFunctionType_FlatTypes(t *testing.T) {
+	fnType := NewFnType(TypeVariable('a'), TypeVariable('b'), TypeVariable('c'))
+	ts := fnType.FlatTypes()
+	correct := Types{TypeVariable('a'), TypeVariable('b'), TypeVariable('c')}
+	assert.Equal(t, ts, correct)
+
+	fnType2 := NewFnType(fnType, TypeVariable('d'))
+	correct = append(correct, TypeVariable('d'))
+	ts = fnType2.FlatTypes()
+	assert.Equal(t, ts, correct)
+}