Re: [Haskell-cafe] avoiding parens in postfix applicative notation

Hi Johannes, The lens library defines (<&>) with very low precedence (1), whereas (<$>) has precedence 4. If you define (<&>) yourself and specify a precedence higher than 4, or just don’t specify a precedence at all, your example will work fine: (<&>) :: Functor f => f a -> (a -> b) -> f b (<&>) = flip fmap "foo" <**> "bar" <&> (,) You can do hanging style too, with no dollar sign: "foo" <**> "bar" <&> \q r -> ..(q, r) If you don’t like defining ad-hoc versions of things like (<&>), you might find the ‘overhang’ library useful: https://hackage.haskell.org/package/overhang-1.0.0/docs/Overhang.html#v:onMa... https://hackage.haskell.org/package/overhang-1.0.0/docs/Overhang.html#v:onMa... The overhang equivalent of (<&>) is ‘onMap’ and it can be used in the same way: import Overhang (onMap) "foo" <**> "bar" `onMap` (,) The code aesthetics around writing a “final" lambda that spans several lines was the driver for creating that library! Jason

On Feb 6, 2018, at 12:37 PM, Neil Mayhew wrote:

On 2018-02-06 07:59 AM, MarLinn wrote:

...

I've been bitten multiple times because of my own invented operators. What was (>>?!) again? Or (^>>>&)? The more I use Haskell the more I tend to solutions like that first dead-simple one.

I agree.

Also, since

func <$> "foo" <*> "bar"

is the lifted equivalent of

func "foo" "bar"

I find it unintuitive to read or write the logic in the opposite order.

Whether we like it or not, Haskell is fundamentally a right-to-left language. Or, to look at it another way, top-down corresponds to left-to-right, and bottom-up corresponds to right-to-left. Perhaps it depends on whether you're a top-down thinker (like me) or a bottom-up thinker. I much prefer `where` to `let`, for example. _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.