Type check

type.go

@@ -0,0 +1,94 @@
+package main
+
+import "fmt"
+
+type Type interface {
+	Equal(Type) bool
+}
+
+type PrimitiveType string
+
+type ListType struct{ t Type }
+
+type QuotedType struct{ t Type }
+
+type FunctionType struct {
+	ret    Type
+	params []Type
+}
+
+// type VariadicListType ListType
+
+type TypeEnvironment map[Id]Type
+
+var (
+	PrimVoid    PrimitiveType = "void"
+	PrimAny     PrimitiveType = "any"
+	PrimBoolean PrimitiveType = "boolean"
+	PrimInteger PrimitiveType = "integer"
+	PrimFloat   PrimitiveType = "float"
+)
+
+func (a *PrimitiveType) Equal(b Type) bool {
+	switch b := b.(type) {
+	case *PrimitiveType:
+		return a == b
+	default:
+		return false
+	}
+}
+
+func (p PrimitiveType) String() string {
+	return string(p)
+}
+
+func (a *ListType) Equal(b Type) bool {
+	switch b := b.(type) {
+	case *ListType:
+		return a.t.Equal(b.t)
+	default:
+		return false
+	}
+}
+
+func (l ListType) String() string {
+	return fmt.Sprintf("[list %v]", l.t)
+}
+
+func (a *QuotedType) Equal(b Type) bool {
+	switch b := b.(type) {
+	case *QuotedType:
+		return a.t.Equal(b.t)
+	default:
+		return false
+	}
+}
+
+func (q QuotedType) String() string {
+	return fmt.Sprintf("[quote %v]", q.t)
+}
+
+func (fa *FunctionType) Equal(b Type) bool {
+	fb, ok := b.(*FunctionType)
+	if !ok {
+		return false
+	}
+	if len(fa.params) != len(fb.params) {
+		return false
+	}
+	for i := range fa.params {
+		if !fa.params[i].Equal(fb.params[i]) {
+			return false
+		}
+	}
+	return fa.ret.Equal(fb.ret)
+}
+
+// func (fa *VariadicListType) Equal(b Type) bool {
+// 	return false
+// }
+//
+// func isVariadic(t Type) bool {
+// 	_, ok := t.(*VariadicListType)
+// 	return ok
+// }