rearrange builtins

builtins/read.go

@@ -0,0 +1,28 @@
+package builtins
+
+import "monkey/object"
+
+import (
+	"os"
+)
+
+// Read ...
+func Read(args ...object.Object) object.Object {
+	if len(args) != 1 {
+		return newError("wrong number of arguments. got=%d, want=1",
+			len(args))
+	}
+
+	arg, ok := args[0].(*object.String)
+	if !ok {
+		return newError("argument to `read` expected to be `str` got=%T", args[0].Type())
+	}
+
+	filename := arg.Value
+	data, err := os.ReadFile(filename)
+	if err != nil {
+		return newError("error reading file: %s", err)
+	}
+
+	return &object.String{Value: string(data)}
+}