Methods on Basic Types in Go

The programming language Go includes a variety of string functions, such as ToUpper() and Split(). Unlike other languages that might define these functions as methods on the string type, Go instead defines them as part of the strings package. Why is this the case?

Simplicity and Flexibility

According to Go's creators, one of the primary reasons for keeping methods outside of basic types like string is to maintain the simplicity and flexibility of the language. Allowing methods on basic types would introduce complexity in terms of how interfaces are handled.

Isolation of Builtin Functionality

Strings, along with other fundamental types in Go, are implemented at the language level. Adding methods to these types would require modifying the language itself, which is undesirable from a maintenance and evolution perspective.

The strings package, on the other hand, provides a convenient and extensible way to add new functionality to strings without altering the underlying type. Custom types that extend string can still access the built-in ToUpper function if desired.

Design Philosophy

Go's design philosophy emphasizes caution and avoiding unnecessary complexity. The decision to keep methods off basic types stemmed from this philosophy, prioritizing simplicity and ease of maintenance over potential syntactic sugar.