Re: Add flipped fmap

What about if you add grep 'flip fmap' ? -Edward Kmett On Wed, Apr 7, 2010 at 8:34 AM, Jesper Louis Andersen < jesper.louis.andersen@gmail.com> wrote:

On Wed, Apr 7, 2010 at 11:13 AM, Bas van Dijk wrote:

...

I would like to propose adding a flipped variant of <$> to Data.Functor:

(<$$>) ∷ Functor f ⇒ f α → (α → β) → f β (<$$>) = flip (<$>)

It is worth doing some simple statistics: There are 5939 hackage packages in my git-repo archive. Of these, there are 10 apps which import Data.Functor directly. The number for Control.Applicative is 418. 'flip\s*<$>' is defined by 6 different packages:

jlouis@jlouis-desktop:~/Projects/hackage$ git grep 'flip\s\+<\$>' | sed -e 's/:.*$//' HXQ-0.18.2.tar.gz.dir/HXQ-0.18.2/src/hxml-0.2/LLParsing.hs HXQ-0.18.2.tar.gz.dir/HXQ-0.18.2/src/hxml-0.2/LLParsing.hs

action-permutations-0.0.0.0.tar.gz.dir/action-permutations-0.0.0.0/Control/Applicative/Permutation.hs

curry-frontend-0.2.9.tar.gz.dir/curry-frontend-0.2.9/src/Curry/Syntax/LLParseComb.lhs

curry-frontend-0.2.9.tar.gz.dir/curry-frontend-0.2.9/src/Curry/Syntax/LLParseComb.lhs ideas-0.5.8.tar.gz.dir/ideas-0.5.8/src/Text/Parsing.hs

uu-parsinglib-2.3.1.tar.gz.dir/uu-parsinglib-2.3.1/src/Text/ParserCombinators/UU/Derived.hs

uu-parsinglib-2.3.1.tar.gz.dir/uu-parsinglib-2.3.1/src/Text/ParserCombinators/UU/Derived.hs

uu-parsinglib-2.3.1.tar.gz.dir/uu-parsinglib-2.3.1/src/Text/ParserCombinators/UU/Derived.hs

uu-parsinglib-2.3.1.tar.gz.dir/uu-parsinglib-2.3.1/src/Text/ParserCombinators/UU/Derived.hs uulib-0.9.12.tar.gz.dir/uulib-0.9.12/src/UU/Parsing/Derived.hs uulib-0.9.12.tar.gz.dir/uulib-0.9.12/src/UU/Parsing/Derived.hs uulib-0.9.12.tar.gz.dir/uulib-0.9.12/src/UU/Parsing/Derived.hs uulib-0.9.12.tar.gz.dir/uulib-0.9.12/src/UU/Parsing/Derived.hs

The confounder is: How many packages would have used the flipped variant had they had access to it. Personally, I wouldn't add it, but it cannot hurt since only 10 hackage packages would potentially be affected by the change. For non-hackage packages, if the hackage packages are taken as a sample, we have 0.1% of the packages affected (fewer, actually).

-- J. _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries