[Haskell-beginners] Representing most types by the same letter

Hi. I'm trying to learn Haskore, and it seems rather odd: Why are most types in the system represented by the same letter, the letter 'T'? For example, instead of a Scale type, a Duration type, and a Pitch type, there is a T type in the Scale module, a T type in the Duration module, and a T type in the Pitch module. It makes the documentation rather challenging to read, because I have to read the link for each appearance of the letter to see what type it is referring to. Is there some theory behind this practice? -- frigidcode.com