Re: Proposal: Add (&) to Data.Function

On Tue, Nov 20, 2012 at 2:20 PM, Johan Tibell wrote:

On Tue, Nov 20, 2012 at 11:11 AM, John Wiegley wrote:

...

And let's not forget that the current <%= operator would turn into <|>=, which is completely unfortunate because it has nothing to do with <|>.

lens currently defines 99 operators. As much as I admire Edward's work, I don't think we should take the interaction of these operators into account when we define a very important, standard operator for composing functions that's supposed to be used by the Haskell ecosystem as a whole.

Yes, lens defines 99 operators. The vast majority of them fall into a common scheme; operator~ for functional update using a well known operatr operator= for an update into state. ) to use a single character symbol. - It is shorter involves less visual noise than |>. This accumulates quite a bit in long chains of them. - Arguably, you can read it off the screen better. - |> from an existing Haskell-semiotics perspective looks like something that involves Control.Applicative. e.g. x |> a = x <|> pure None of those are lens specific. Now, were I being selfish, and caring solely about maximize the consistency of my own design, I'd be pushing for (%), because (%) is similarly under-utilized but for the one unfortunate occurrence in Data.Ratio that encourages everyone to screw up and make useless Ratio Int's and provides the nice `mod` denotation when (%=)'d I often chain this & a lot, when defining records or working with zippers foo & bar .~ baz & quux .~ quaffle & ... looks a lot less like linenoise than the longer foo |> bar .~ baz |> quux .~ quaffle |> ... In fact it looks better than the % i championed originally, because it reads off the screen much better. At this time I have no intention of changing %=, etc. to consistently use & instead of %. If (|>) was picked, those operators would still be (%=), not (|>=). I clung to consistency in my initial choice of (%) over (|>) originally, but in practice what I found I liked was the terseness of the one character operator, not necessarily the consistency with (%=), etc. I've already conceded that inconsistency between that (&) and (%=), etc. in lens is better than slavish consistency, but I really don't like using a two character operator where a 1 character operator will do. -Edward