refactor objects

internal/object/object.go

@@ -54,17 +54,14 @@ func (t Type) String() string {
 	}
 }
 
-// Comparable is the interface for comparing two Object and their underlying
-// values. It is the responsibility of the caller (left) to check for types.
-// Returns `true` iif the types and values are identical, `false` otherwise.
+// Comparable is the interface for objects to implement suitable comparisons
 type Comparable interface {
 	Compare(other Object) int
 }
 
-// Immutable is the interface for all immutable objects which must implement
-// the Clone() method used by binding names to values.
-type Immutable interface {
-	Clone() Object
+// Copyable is the interface for creating copies of objects
+type Copyable interface {
+	Copy() Object
 }
 
 // Object represents a value and implementations are expected to implement
@@ -76,10 +73,9 @@ type Object interface {
 	Inspect() string
 }
 
-// Hashable is the interface for all hashable objects which must implement
-// the HashKey() method which returns a HashKey result.
-type Hashable interface {
-	HashKey() HashKey
+// Hasher is the interface for objects to provide suitable hash keys
+type Hasher interface {
+	Hash() HashKey
 }
 
 // BuiltinFunction represents the builtin function type