24 July 2013

Python should have Haskell's $ operator

In Python, I often want to repeatedly say "apply some function to the remainder of the current statement". Think foo(bar(baz(qux, quux))). In my text editor, which mostly automatically handles the parenthesis correctly, this is a quick thing to type.

Within IPython, statements like that are tedious. IPython does have a limited version of this in its automatic parenthesis feature. Notice how many syntax error gotchas lurk in those examples.

Haskell's $ operator is pretty sweet. All of the following are equivalent in Haskell:

putStrLn (show (1 + 1))
putStrLn (show $ 1 + 1)
putStrLn $ show (1 + 1)
putStrLn $ show $ 1 + 1

Python should adopt Haskell's $ operator. That is, the following should be equivalent:

foo(bar(baz(qux, quux)))
foo $ bar $ baz(qux, quux)
foo $ bar $ baz $ qux, quux
Though odd looking, there's easy consistency for unary functions:
foo $

Haters of the new-ish print might find respite in print $ foo.

Subscribe Subscribe to The Return of Agent Zlerich