Copyright | (c) Gershom Bazerman 2018 |
---|---|

License | BSD-style |

Maintainer | libraries@haskell.org |

Portability | portable |

Safe Haskell | Trustworthy |

Language | Haskell98 |

This module provides efficient containers-based functions on the list type.

In the documentation, \(n\) is the number of elements in the list while
\(d\) is the number of distinct elements in the list. \(W\) is the number
of bits in an `Int`

.

# Documentation

nubOrd :: Ord a => [a] -> [a] Source #

\( O(n \log d) \). The `nubOrd`

function removes duplicate elements from a
list. In particular, it keeps only the first occurrence of each element. By
using a `Set`

internally it has better asymptotics than the standard
`nub`

function.

#### Strictness

`nubOrd`

is strict in the elements of the list.

#### Efficiency note

When applicable, it is almost always better to use `nubInt`

or `nubIntOn`

instead of this function, although it can be a little worse in certain
pathological cases. For example, to nub a list of characters, use

nubIntOn fromEnum xs

nubOrdOn :: Ord b => (a -> b) -> [a] -> [a] Source #

The `nubOrdOn`

function behaves just like `nubOrd`

except it performs
comparisons not on the original datatype, but a user-specified projection
from that datatype.

#### Strictness

`nubOrdOn`

is strict in the values of the function applied to the
elements of the list.

nubInt :: [Int] -> [Int] Source #

\( O(n \min(d,W)) \). The `nubInt`

function removes duplicate `Int`

values from a list. In particular, it keeps only the first occurrence
of each element. By using an `IntSet`

internally, it attains better
asymptotics than the standard `nub`

function.

See also `nubIntOn`

, a more widely applicable generalization.

#### Strictness

`nubInt`

is strict in the elements of the list.

nubIntOn :: (a -> Int) -> [a] -> [a] Source #

The `nubIntOn`

function behaves just like `nubInt`

except it performs
comparisons not on the original datatype, but a user-specified projection
from that datatype. For example, `nubIntOn `

can be used to
nub characters and typical fixed-with numerical types efficiently.`fromEnum`

#### Strictness

`nubIntOn`

is strict in the values of the function applied to the
elements of the list.