Flipped function application

[Edward Kmett]

When I tallied the vote after last time adding it as (&) won more than half the vote, but it was clearly something that evoked a very strong response out of a sizeable portion of the community, so we backed down. At the time there was no maintainer for base. Now we have the core libraries committee.

All the alternate names polled much worse than (&), so bike shedding the name won't fix it. ;)

How about this: 

I'll ask the core libraries committee for a judgment, but recuse myself.

-Edward

> On Oct 9, 2013, at 3:23 PM, Dan Burton <danburton.email at gmail.com> wrote:
> 
> What were the arguments against (&)? Were they about that choice of symbol in particular, or about the presence of such an operator at all? If the former, then we can keep putting different colors on the bikeshed until we find one everyone likes. If the latter, then I guess we just stick with telling people to import it from lens or diagrams or whatever.
> 
> I believe my previous participation in that discussion was to promote (|>), but at this point I don't really care what it's called, I just think that this operator under any symbolic name should be present in an easily accessible location, preferably in base libs.
> 
> 
> -- Dan Burton
> 
> 
>> On Wed, Oct 9, 2013 at 12:00 PM, Edward Kmett <ekmett at gmail.com> wrote:
>> Attempting to get (&) added to Data.Function led to a rather profound amount of disagreement last time it was brought up, so eventually we just let the status quo continue.
>> 
>> -Edward
>> 
>>> On Oct 9, 2013, at 2:52 PM, Oren Ben-Kiki <haskell-oren at ben-kiki.org> wrote:
>>> 
>>> & is already used for this purpose by the Lens library...
>>> 
>>> 
>>>> On Wed, Oct 9, 2013 at 9:51 PM, Wvv <vitea3v at rambler.ru> wrote:
>>>> It's looking very strange, that such easy function as flipped function
>>>> application is still absent at the base.
>>>> 
>>>> 
>>>> x # f = f x
>>>> infixl 1 #     -- infix (#) must conflict neither ($), nor (.)
>>>> 
>>>> We could add it to Data.Functions and probably to Prelude.
>>>> 
>>>> It is very useful function to get rid of parentheses (1); "object looking"
>>>> record style (2); left-to-right function reading style (3); nice looking
>>>> last argument-data (4)
>>>> 
>>>> 1) xs # map $ someLong function
>>>>    x # some . function . composition
>>>> 2) car # color
>>>> 3) myString # lines # map words # concat # filter myFilter # unwords
>>>> 4) eitherData # either (left long function) (right long function)
>>>> 
>>>> 
>>>> Many of possible names are already busy. I made the review of possible
>>>> names:
>>>> 
>>>>   #    - free; disadvantage: possible conflicts with Magic Hash
>>>>   ##  - free; disadvantage: heavy looking; possible conflicts with Magic
>>>> Hash
>>>> `to`  - free; disadvantage: not easy to read composite functions
>>>>  <:    - free;
>>>>  &     - free; (conflict with fgl package) disadvantage: looking like
>>>> boolean operator
>>>>  .:     - free;
>>>>  .:.    - free; disadvantage: many dots
>>>>  <-|  - free; disadvantage: long name
>>>>  <+   - free;
>>>>  <~   - free;
>>>>  :~    - free;
>>>>  -|-   - free; disadvantage: bad looking;
>>>>  %    - busy: Data.Ratio
>>>>  %%  - free; disadvantage: heavy looking;
>>>>   ^    - busy: Prelude
>>>>  .^.   - free;
>>>>  ^^^ - free; disadvantage: long name
>>>>  |.|    - free; disadvantage: strange looking;
>>>>   *$    - free; disadvantage: looking like ($)
>>>>  <|    - busy: Data.Sequence
>>>>  <     - busy: Prelude
>>>>  <<   - busy: Text.Html; Text.XHtml.* from html and xhtml package
>>>>  <<< - busy: Control.Category
>>>>  *     - busy: Prelude
>>>>  **   - busy: Prelude
>>>>  ***  - busy: Control.Arrow
>>>>  <*>  - busy: Control.Applicative
>>>>  <**> - busy: Control.Applicative
>>>>   !!    - busy: Prelude
>>>>   -|   - busy: Control.Parallel.Strategies
>>>>  your suggestion  - free;
>>>> 
>>>> I prefer (#) , then (.:) and then (<:).
>>>> 
>>>> What do you prefer?
>>>> 
>>>> Possible looking (copy to your editor to taste them):
>>>> 
>>>> 2.1 # max 50 # cos # tan # negate # ceiling
>>>> 
>>>> 2.1 ## max 50 ## cos ## tan ## negate ## ceiling
>>>> 
>>>> 2.1 `to` max 50 `to` cos `to` tan `to` negate `to` ceiling
>>>> 
>>>> 2.1 <: max 50 <: cos <: tan <: negate <: ceiling
>>>> 
>>>> 2.1 & max 50 & cos & tan & negate & ceiling
>>>> 
>>>> 2.1 .: max 50 .: cos .: tan .: negate .: ceiling
>>>> 
>>>> 2.1 .:. max 50 .:. cos .:. tan .: negate .:. ceiling
>>>> 
>>>> 2.1 <-| max 50 <-| cos <-| tan <-| negate <-| ceiling
>>>> 
>>>> 2.1 <+ max 50 <+ cos <+ tan <+ negate <+ ceiling
>>>> 
>>>> 2.1 <~ max 50 <~ cos <~ tan <~ negate <~ ceiling
>>>> 
>>>> 2.1 % max 50 % cos % tan % negate % ceiling
>>>> 
>>>> 2.1 %% max 50 %% cos %% tan %% negate %% ceiling
>>>> 
>>>> 2.1 .^. max 50 .^. cos .^. tan .^. negate .^. ceiling
>>>> 
>>>> 2.1 :~ max 50 :~ cos :~ tan :~ negate :~ ceiling
>>>> 
>>>> 2.1 |.| max 50 |.| cos |.| tan |.| negate |.| ceiling
>>>> 
>>>> 2.1 -|- max 50 -|- cos -|- tan -|- negate -|- ceiling
>>>> 
>>>> 
>>>> 
>>>> --
>>>> View this message in context: http://haskell.1045720.n5.nabble.com/Flipped-function-application-tp5738131.html
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