Proposal: Add (&) to Data.Function
danburton.email at gmail.com
Tue Nov 20 21:32:42 CET 2012
> Functional metapost called it (#). But for me (>>>) is ok. It is even more
> descriptive than (&).
The reason I feel that >>> is inadequate is because it requires that you
use either parens or $ in order to finally apply the chain of functions to
a value. Also, being part of a typeclass can scare newcomers from
(foo >>> bar >>> baz) val
foo >>> bar >>> baz $ val
Part of the reason I like |> is because it *is* a little more clutter-y
than &. This forces you to use it prudently, with adequate whitespace. For
example, when I was writing a StackOverflow answer a few days ago, I
found that using this operator was unreadable unless I used additional
newlines. Lining up the |> operators actually produces a rather nice visual
effect, as if you were entering each transformation at a command prompt.
The vertical bars lining up is also nice. Consider the "butt-ugly" code
(according to Thomas):
("hello","world") & _1.traverse %~ toUpper & _2 .~ 42
Rewritten with whitespace, it can look much prettier:
|> _1.traverse %~ toUpper
|> _2 .~ 42
This style is reminiscent of the style often used for long chains of
object-oriented method calls.
& works just as well with the additional whitespace, but complaints about
the line noise caused by |> go away also.
-- Dan Burton
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