# Num instance for functions

### From HaskellWiki

(Difference between revisions)

(Categroy:FAQ) |
(Category:FAQ, misspelling reflected the change precisely, but it was not the intended one) |

## Revision as of 15:34, 18 December 2007

Some people have argued, thatNum

(->)

to add functions nicely, say for

f, g :: Num a => b -> a

you would define

(f+g) x = f x + g x

fromInteger

fromInteger = const

numeric literals would also denote constant functions. This allows

f+2 == \x -> f x + 2

Even nicer, the mathematically established notation of omitting the multiplication dot

2(x+y) :: Integer

will now be parsed by a Haskell compiler to the most obvious meaning

2 :: Integer

! :-)

## 1 Note

This article is in category Proposals in order to show people that this idea was already proposed, but that one should think twice implementing it. There should be a category Counterproposals.