refactor: move common func methods to dsl/ops/func.go

Author: tyru

dsl/ops/func.go

@@ -0,0 +1,11 @@
+package ops
+
+type funcBase string
+
+func (f *funcBase) String() string {
+	return string(*f)
+}
+
+func (*funcBase) IsMacro() bool {
+	return false
+}

dsl/ops/func_do.go

@@ -8,23 +8,15 @@ import (
 )
 
 func init() {
-	opName := doOp("do")
-	DoOp = &opName
 	opsMap["do"] = DoOp
 }
 
-type doOp string
-
-// DoOp is "do" operation
-var DoOp *doOp
-
-func (*doOp) String() string {
-	return string(*DoOp)
+type doOp struct {
+	funcBase
 }
 
-func (*doOp) IsMacro() bool {
-	return false
-}
+// DoOp is "do" operation
+var DoOp = &doOp{funcBase("do")}
 
 func (*doOp) Bind(args ...types.Value) (types.Expr, error) {
 	sig := make([]types.Type, 0, len(args))