Added a Cloner interface for FunctionType and Record

Author: chewxy

functionType.go

@@ -104,3 +104,21 @@ func (t *FunctionType) FlatTypes() Types {
 	}
 	return retVal
 }
+
+// Clone implements Cloner
+func (t *FunctionType) Clone() interface{} {
+	retVal := new(FunctionType)
+
+	if ac, ok := t.a.(Cloner); ok {
+		retVal.a = ac.Clone().(Type)
+	} else {
+		retVal.a = t.a
+	}
+
+	if bc, ok := t.b.(Cloner); ok {
+		retVal.b = bc.Clone().(Type)
+	} else {
+		retVal.b = t.b
+	}
+	return retVal
+}

functionType_test.go

@@ -87,3 +87,12 @@ func TestFunctionType_FlatTypes(t *testing.T) {
 	ts = fnType2.FlatTypes()
 	assert.Equal(t, ts, correct)
 }
+
+func TestFunctionType_Clone(t *testing.T) {
+	fnType := NewFnType(TypeVariable('a'), TypeVariable('b'), TypeVariable('c'))
+	assert.Equal(t, fnType.Clone(), fnType)
+
+	rec := NewRecordType("", TypeVariable('a'), NewFnType(TypeVariable('a'), TypeVariable('b')), TypeVariable('c'))
+	fnType = NewFnType(rec, rec)
+	assert.Equal(t, fnType.Clone(), fnType)
+}

hm.go

@@ -2,6 +2,11 @@ package hm
 
 import "github.com/pkg/errors"
 
+// Cloner is any type that can clone
+type Cloner interface {
+	Clone() interface{}
+}
+
 // Fresher keeps track of all the TypeVariables that has been generated so far. It has one method - Fresh(), which is to create a new TypeVariable
 type Fresher interface {
 	Fresh() TypeVariable

type.go

@@ -22,7 +22,7 @@ type Substitutable interface {
 	FreeTypeVar() TypeVarSet
 }
 
-// TypeConst are the default implementation of a constant type. Feel free to implement your own
+// TypeConst are the default implementation of a constant type. Feel free to implement your own. TypeConsts should be immutable (so no pointer types plz)
 type TypeConst string
 
 func (t TypeConst) Name() string                            { return string(t) }
@@ -116,3 +116,20 @@ func (t *Record) Format(f fmt.State, c rune) {
 }
 
 func (t *Record) String() string { return fmt.Sprintf("%v", t) }
+
+// Clone implements Cloner
+func (t *Record) Clone() interface{} {
+	retVal := new(Record)
+	ts := BorrowTypes(len(t.ts))
+	for i, tt := range t.ts {
+		if c, ok := tt.(Cloner); ok {
+			ts[i] = c.Clone().(Type)
+		} else {
+			ts[i] = tt
+		}
+	}
+	retVal.ts = ts
+	retVal.name = t.name
+
+	return retVal
+}