restructure project

internal/builtins/hash.go

@@ -0,0 +1,22 @@
+package builtins
+
+import (
+	"monkey/internal/object"
+	"monkey/internal/typing"
+)
+
+// HashOf ...
+func HashOf(args ...object.Object) object.Object {
+	if err := typing.Check(
+		"hash", args,
+		typing.ExactArgs(1),
+	); err != nil {
+		return newError(err.Error())
+	}
+
+	if hash, ok := args[0].(object.Hashable); ok {
+		return &object.Integer{Value: int64(hash.HashKey().Value)}
+	}
+
+	return newError("TypeError: hash() expected argument #1 to be hashable")
+}