Re: [xmonad] Re: Compile-time verification of keymaps

* On Wednesday, March 24 2010, Ivan Miljenovic wrote:

On 24 March 2010 10:25, wrote:

...

Surely this solution is too complicated, given that "-fwarn-overlapping-patterns" works perfectly well and is built into GHC.

Does that work if addKeysP is used? (Does gwern's patch work in that case?)

The quasiquoter does work for either style of keybinding, though for that purpose the implicit Map.fromList shouldn't be included in the QQ. I don't quite understand how -fwarn-overlapping-patterns can be used to avoid overlapping keybinds: you suggest replacing the (Map Key (X ())) with a function (Key -> Maybe (X ())) (with the maybe possibly added by catching pattern match failures)? Performance probably doesn't matter here, but I believe pattern matches are tried one after the other, as compared to Data.Map which is a bit smarter than that. More importantly, xmonad needs to be able to tell the xserver which keys it will be listening to, which may be a bit awkward with the function approach. But neither the function or the QQ approaches seem to be terribly composable (in that they miss overlapped bindings if you try to combine bindings defined in separate places). The use of HList instead looks like it could avoid that and still enforce no-duplicates no matter where the keybindings come from, though there would be a bit of effort involved to generate the record keys. -- Adam