[recursive]

> The Maybe type constructor is predefined by Haskell as [...]

It's hard for me to imagine a reader that understands the rest of this jargon, presented without explanation, who does not know what `Maybe` is.

[dan-robertson]

1. People often struggle to target the things they write well towards a specific group of people and that often leads to this sort of thing.

2. I think when I came across this when it was posted to hacker news 5-10 years ago, I didn’t know any Haskell or any ML language and I didn’t know the maths but the program was small enough and direct enough that I think I managed to puzzle through a lot of it just by trying to match the code to the type signature (though this isn’t really sufficient to get a good feel for what is going on)

[wyager]

Probably targeted at people who use other ML family languages (although this isn't a large crowd).

[maxiepoo]

A mathematician that has only used a type theory like Coq or Agda and never Haskell.