[jiiam]

> Those don't seem to be names of parameters, but rather of types. It's missing parameter names entirely.

The rest of the definition is at the end, to see it as a whole:

  splitAt :: Eq a => a -> [a] -> [[a]]

  splitAt x xs = ...

To clarify, I assumed that by using the constraint `Eq a` and the name splitAt there was no need for extra clarification in the names of the parameters but apparently I was wrong.

[gmfawcett]

I think some of the confusion is because you're referring to the type variables as parameters. Parameters and type variables are not the same thing. A is a type variable, X is a parameter in your example.

[theCodeStig]

No, you're right. It is perfectly clear from the type signature