restructure project

internal/builtins/chr.go

@@ -0,0 +1,21 @@
+package builtins
+
+import (
+	"fmt"
+	"monkey/internal/object"
+	"monkey/internal/typing"
+)
+
+// Chr ...
+func Chr(args ...object.Object) object.Object {
+	if err := typing.Check(
+		"chr", args,
+		typing.ExactArgs(1),
+		typing.WithTypes(object.INTEGER_OBJ),
+	); err != nil {
+		return newError(err.Error())
+	}
+
+	i := args[0].(*object.Integer)
+	return &object.String{Value: fmt.Sprintf("%c", rune(i.Value))}
+}