[marginalia_nu]

> Eh, I consider Java to be barely typed too. If you have a variable of type Foo, the type system doesn't even guarantee that you have a Foo in there (it might be null). The whole point of a type system, in my mind, is to guarantee that I have that Foo!

That seems a rather arbitrary limitation. When Java says Foo, it would translate to what you would consider Maybe<Foo>. How you represent types, and what that representation implies is a matter of semantics.

That said, Java's type system is pretty dang weird, especially generics.

> This oft-repeated exaggeration needs to stop. Using monads does not require a PhD in category theory. If you can understand Promises in JavaScript, then you can grasp how IO works in Haskell.

The concepts themselves aren't particularly hard to grok, but the more academic side of functional programming (i.e. Haskell) is comically inaccessible, mostly due to jargon (monads aren't even that bad compared to something like kleisli arrows).

[tshaddox]

"Maybe<Foo>" doesn't have the same problem as Java nulls though, because with an optional type the type system would force you to always handle the possibility of the value not being present. With Java nulls you just get a runtime error if you try to do certain things with something that turns out to be null.

Incidentally, Java does have Optional, and codebases which use it consistently are vastly better to work with. https://docs.oracle.com/javase/8/docs/api/java/util/Optional...