I hear they are good, make it easier to maintain code-bases. Most often I reach for python to get the job done. Does anyone have experiences with functional languages for larger projects?
In particular I am interested to learn more on how to handle databases, and writing to them and what patterns they come up with. Is a database handle you can write to not … basically mutable state, the arch-nemesis of functional languages?
Are functional languages only useful with an imperative shell?
Access to an external database is a kind of effect. In functional terms, you’d use a monad to represent this, though in Koka you’d define an effect for it. In either case, it becomes part of the function signature.
A “pure” function could instead work around it by returning (without executing) a query, accepting a state and returning a new, modified state, or otherwise returning some kind of commands to the caller without directly querying the database.