Donald Bruce Stewart wrote:
Perhas you'd like to put up a Style page on thew new Haskell wiki, perhaps under the Idioms category?
I cannot promise it, but I'll try. If someone else is willing to do it, I would support this. Rob Dockins wrote:
I understood that part of the guidelines as a pleading for Maybe.
Humm. Well clearly I read it the opposite way. I suppose that means that whatever technique is being recommended should be put forth with more clarity ;-)
done (use Maybe or another Monad) Andrew Bromage wrote:
So, for example, f (g (h x)) can be expressed well as:
f . g $ h x -- only use if you need to distinguish h f . g . h $ x -- better
I see this differently. Expressions may be succinct! I find "$" and "." similar enough for non-obfuscation. But I collect cases where "$" does not work (i.e. for the kind #). Bad would be cases where "$" works differently than (reasonably) expected. John Meacham wrote:
f x = ... y ... where Just y = Map.lookup x theMap
now if the lookup fails you automatically get an error message pointing to the exact line number of the failure. or if the failure message of the routine is more important than the source location you can do
f x = ... y ... where Identity y = Map.lookup x theMap
These are potential runtime errors, that may be not so obvious to see in the source (ie. for user defined types) and even the compiler (ghc) does not emit a warning. Thanks for all your comments Christian