Version 2 (modified by malcolm.wallace@…, 9 years ago) (diff) |
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# Flexible Partial Application

Are there any subtle reasons for why something like the following couldn't be allowed?

> foo x y z w = ... > bar x w = foo x _ _ w

I.e. a more flexible version of partial application. This would be translated to

> bar x w = \y z -> foo x y z w

I.e a function which takes the "_" parameters in the same order they were encountered in the function application.

## Related proposals

- feature request for ghc at this ticket
- conflicts with MagicUnderscore

## Pros

## Cons

One can usually assume **id e = e**, for any **e**, but

id (f _ x) y === id (\y->f y x) y === f y x /= f _ x y === \z -> f z x y

Or would **(f _ x) y** and **f _ x y** maybe be different? That would fix the problem above, while introducing another.