Re: Proposal: add `on` to the Prelude

+1 for adding `on` to the Prelude. On 2019-09-11 00:59, David Feuer wrote:

Indeed, there are a lot more conflicts than I'd have expected. Ignoring functions with the same type, Hoogle shows this name in the below packages. I have no sense of the overall significance of the specific packages or (equally importantly) of the `on` function within each.

haskell-gi-base: on :: forall object info m . (GObject object, MonadIO m, SignalInfo info) => object -> SignalProxy object info -> HaskellCallbackType info -> m SignalHandlerId

brick: on :: Color -> Color -> Attr

esqueletto: on :: SqlExpr (Value Bool) -> SqlQuery ()

relational-query (both): on :: MonadQuery m => Predicate Flat -> m () on :: MonadQuery m => QueryA m (Predicate Flat) ()

threepenny-gui: on :: (element -> Event a) -> element -> (a -> UI void) -> UI ()

miso: on :: MisoString -> Decoder r -> (r -> action) -> Attribute action

wild-bind: on :: i -> v -> Binder i v ()

massiv-io: on :: Pixel X Bit

selda-postgresql: on :: Text -> Text -> PGConnectInfo

On Tue, Sep 10, 2019, 6:42 PM Ryan Trinkle mailto:ryan.trinkle@gmail.com> wrote:

One note: this does conflict with some other libraries, for instance GTK2HS

On Tue, Sep 10, 2019 at 6:26 PM chessai . mailto:chessai1996@gmail.com> wrote:

+1

On Tue, Sep 10, 2019, 5:53 PM David Feuer mailto:david.feuer@gmail.com> wrote:

Every time I reach for Data.Function.on, I feel like a total dolt for having to import a module to get a function whose implementation is barely longer than the import. And it's a really good function too! Can we please add it to the Prelude?

  on :: (b -> b -> c) -> (a -> b) -> a -> a -> c   (.*.) `on` f = \x y -> f x .*. f y _______________________________________________ Libraries mailing list Libraries@haskell.org mailto:Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

_______________________________________________ Libraries mailing list Libraries@haskell.org mailto:Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

_______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries