> Why aren't S and R just called SendCapability and ReceiveCapability? Let's see how it reads if they were? data SendCapability a data ReceiveCapabili

> Why aren't S and R just called SendCapability and ReceiveCapability? Let's see how it reads if they were? data SendCapability a data ReceiveCapability a newCaps :: (ReceiveCapability a ⊸ SendCapability a ⊸ IO ()) ⊸ IO () send :: SendCapability a ⊸ a ⊸ IO () receive :: ReceiveCapability a ⊸ (a ⊸ IO ()) ⊸ IO () Personally, I find that less readable - most of the space of the line is taken up with the two names, it's harder to keep track of the shape of it (in particular, matching parens), and it doesn't communicate anything more when you'll need to read the accompanying paragraph anyway. That's not to say S and R are good names in a real program - name length should track scope, and type names have pretty broad scope (global but module-constrained), so they should usually be comparatively long. `SendCap` and `RecvCap` might be a good compromise, in that context. Type variables (like the `a` here) are local to the individual type signature (and, with -XScopedTypeVariables, possibly the accompanying definition) and so should be shorter. One letter may be too extreme - `a` does a fine job conveying "whatever you care to be dealing with" but `msg` might be even better in this particular case.