Safe Haskell | None |
---|---|

Language | Haskell2010 |

## Synopsis

- (^?!) :: (HasCallStack, Is k An_AffineFold) => s -> Optic' k is s a -> a

# Documentation

(^?!) :: (HasCallStack, Is k An_AffineFold) => s -> Optic' k is s a -> a infixl 8 Source #

Perform an *UNSAFE* `head`

of an affine fold assuming that it is there.

`>>>`

4`Left 4 ^?! _Left`

`>>>`

'l'`"world" ^?! ix 3`

`>>>`

*** Exception: (^?!): empty affine fold ...`[] ^?! _head`

*Since: 0.3*