Copyright	(c) 2011-2015 Edward Kmett (c) 2018-2021 Kowainik
License	MIT
Maintainer	Kowainik <xrom.xkov@gmail.com>
Stability	Experimental
Portability	Portable
Safe Haskell	Safe
Language	Haskell2010

Relude.Extra.Foldable1

Description

Foldable1 is a typeclass like Foldable but for non-empty structures. For example, NonEmpty, Identity.

Foldable1 has all type-safe and total methods like head1, maximum1 in contradiction with Foldable.

Since: 0.3.0

Synopsis

class Foldable f => Foldable1 f where
- foldMap1 :: Semigroup m => (a -> m) -> f a -> m
- fold1 :: Semigroup m => f m -> m
- foldr1 :: (a -> b -> b) -> b -> f a -> b
- toNonEmpty :: f a -> NonEmpty a
- head1 :: f a -> a
- last1 :: f a -> a
- maximum1 :: Ord a => f a -> a
- minimum1 :: Ord a => f a -> a
- maximumOn1 :: Ord b => (a -> b) -> f a -> a
- minimumOn1 :: Ord b => (a -> b) -> f a -> a
foldl1' :: (a -> a -> a) -> NonEmpty a -> a
average1 :: forall a f. (Foldable1 f, Fractional a) => f a -> a

Documentation

class Foldable f => Foldable1 f where Source #

The class of foldable data structures that cannot be empty.

Since: 0.3.0

Minimal complete definition

foldMap1

Methods

foldMap1 :: Semigroup m => (a -> m) -> f a -> m Source #

Map each element of the non-empty structure to a semigroup, and combine the results.

>>> foldMap1 SG.Sum (1 :| [2, 3, 4])
Sum {getSum = 10}
>>> foldMap1 show (123 :| [456, 789, 0])
"1234567890"

fold1 :: Semigroup m => f m -> m Source #

Combine the elements of a non-empty structure using a semigroup.

>>> fold1 (1 :| [2, 3, 4 :: SG.Sum Int])
Sum {getSum = 10}
>>> fold1 (4 :| [5, 10 :: SG.Product Int])
Product {getProduct = 200}

foldr1 :: (a -> b -> b) -> b -> f a -> b Source #

Combines the elements of a non-empty structure using a binary function f.

>>> foldr1 (+) 0 (1 :| [2, 3])
6
>>> foldr1 (+) 1 $ Identity 3
4

Since: 1.0.0.0

toNonEmpty :: f a -> NonEmpty a Source #

Convert a non-empty data structure to a NonEmpty list.

>>> toNonEmpty (Identity 2)
2 :| []

head1 :: f a -> a Source #

The first element of a non-empty data structure.

>>> head1 (1 :| [2, 3, 4])
1

last1 :: f a -> a Source #

The last element of a non-empty data structure.

>>> last1 (1 :| [2, 3, 4])
4

maximum1 :: Ord a => f a -> a Source #

The largest element of a non-empty data structure.

>>> maximum1 (32 :| [64, 8, 128, 16])
128

minimum1 :: Ord a => f a -> a Source #

The smallest element of a non-empty data structure.

>>> minimum1 (32 :| [64, 8, 128, 16])
8

maximumOn1 :: Ord b => (a -> b) -> f a -> a Source #

The largest element of a non-empty data structure with respect to the given comparison function.

>>> maximumOn1 abs (0 :| [2, 1, -3, -2])
-3

Since: 1.0.0.0

minimumOn1 :: Ord b => (a -> b) -> f a -> a Source #

The smallest element of a non-empty data structure with respect to the given comparison function.

>>> minimumOn1 abs (0 :| [2, 1, -3, -2])
0

Since: 1.0.0.0

Instances

Instances details

IsListError => Foldable1 [] Source #	⚠️CAUTION⚠️ This instance is for custom error display only. `Foldable1` is not supposed to be used with the lists. In case it is used by mistake, the user will see the following: `>>>` `head1 [1, 2, 3]`... ... The methods of the 'Foldable1' type class work with non-empty containers. However, one of the 'Foldable1' functions is applied to the List. ... Possible fixes: * Replace [] with one of the: 'NonEmpty', 'Identity', '(c,)', 'Compose f g', 'Product f g', 'Sum f g' * Or use 'Foldable' class for your own risk. ... Since: 0.6.0.0
Instance details Defined in Relude.Extra.Foldable1 Methods foldMap1 :: Semigroup m => (a -> m) -> [a] -> m Source # fold1 :: Semigroup m => [m] -> m Source # foldr1 :: (a -> b -> b) -> b -> [a] -> b Source # toNonEmpty :: [a] -> NonEmpty a Source # head1 :: [a] -> a Source # last1 :: [a] -> a Source # maximum1 :: Ord a => [a] -> a Source # minimum1 :: Ord a => [a] -> a Source # maximumOn1 :: Ord b => (a -> b) -> [a] -> a Source # minimumOn1 :: Ord b => (a -> b) -> [a] -> a Source #
Foldable1 Identity Source #	Since: 0.3.0
Instance details Defined in Relude.Extra.Foldable1 Methods foldMap1 :: Semigroup m => (a -> m) -> Identity a -> m Source # fold1 :: Semigroup m => Identity m -> m Source # foldr1 :: (a -> b -> b) -> b -> Identity a -> b Source # toNonEmpty :: Identity a -> NonEmpty a Source # head1 :: Identity a -> a Source # last1 :: Identity a -> a Source # maximum1 :: Ord a => Identity a -> a Source # minimum1 :: Ord a => Identity a -> a Source # maximumOn1 :: Ord b => (a -> b) -> Identity a -> a Source # minimumOn1 :: Ord b => (a -> b) -> Identity a -> a Source #
Foldable1 NonEmpty Source #	Since: 0.3.0
Instance details Defined in Relude.Extra.Foldable1 Methods foldMap1 :: Semigroup m => (a -> m) -> NonEmpty a -> m Source # fold1 :: Semigroup m => NonEmpty m -> m Source # foldr1 :: (a -> b -> b) -> b -> NonEmpty a -> b Source # toNonEmpty :: NonEmpty a -> NonEmpty a Source # head1 :: NonEmpty a -> a Source # last1 :: NonEmpty a -> a Source # maximum1 :: Ord a => NonEmpty a -> a Source # minimum1 :: Ord a => NonEmpty a -> a Source # maximumOn1 :: Ord b => (a -> b) -> NonEmpty a -> a Source # minimumOn1 :: Ord b => (a -> b) -> NonEmpty a -> a Source #
Foldable1 ((,) c) Source #	Since: 0.3.0
Instance details Defined in Relude.Extra.Foldable1 Methods foldMap1 :: Semigroup m => (a -> m) -> (c, a) -> m Source # fold1 :: Semigroup m => (c, m) -> m Source # foldr1 :: (a -> b -> b) -> b -> (c, a) -> b Source # toNonEmpty :: (c, a) -> NonEmpty a Source # head1 :: (c, a) -> a Source # last1 :: (c, a) -> a Source # maximum1 :: Ord a => (c, a) -> a Source # minimum1 :: Ord a => (c, a) -> a Source # maximumOn1 :: Ord b => (a -> b) -> (c, a) -> a Source # minimumOn1 :: Ord b => (a -> b) -> (c, a) -> a Source #
(Foldable1 f, Foldable1 g) => Foldable1 (Product f g) Source #	Since: 0.3.0
Instance details Defined in Relude.Extra.Foldable1 Methods foldMap1 :: Semigroup m => (a -> m) -> Product f g a -> m Source # fold1 :: Semigroup m => Product f g m -> m Source # foldr1 :: (a -> b -> b) -> b -> Product f g a -> b Source # toNonEmpty :: Product f g a -> NonEmpty a Source # head1 :: Product f g a -> a Source # last1 :: Product f g a -> a Source # maximum1 :: Ord a => Product f g a -> a Source # minimum1 :: Ord a => Product f g a -> a Source # maximumOn1 :: Ord b => (a -> b) -> Product f g a -> a Source # minimumOn1 :: Ord b => (a -> b) -> Product f g a -> a Source #
(Foldable1 f, Foldable1 g) => Foldable1 (Sum f g) Source #	Since: 0.3.0
Instance details Defined in Relude.Extra.Foldable1 Methods foldMap1 :: Semigroup m => (a -> m) -> Sum f g a -> m Source # fold1 :: Semigroup m => Sum f g m -> m Source # foldr1 :: (a -> b -> b) -> b -> Sum f g a -> b Source # toNonEmpty :: Sum f g a -> NonEmpty a Source # head1 :: Sum f g a -> a Source # last1 :: Sum f g a -> a Source # maximum1 :: Ord a => Sum f g a -> a Source # minimum1 :: Ord a => Sum f g a -> a Source # maximumOn1 :: Ord b => (a -> b) -> Sum f g a -> a Source # minimumOn1 :: Ord b => (a -> b) -> Sum f g a -> a Source #
(Foldable1 f, Foldable1 g) => Foldable1 (Compose f g) Source #	Since: 0.3.0
Instance details Defined in Relude.Extra.Foldable1 Methods foldMap1 :: Semigroup m => (a -> m) -> Compose f g a -> m Source # fold1 :: Semigroup m => Compose f g m -> m Source # foldr1 :: (a -> b -> b) -> b -> Compose f g a -> b Source # toNonEmpty :: Compose f g a -> NonEmpty a Source # head1 :: Compose f g a -> a Source # last1 :: Compose f g a -> a Source # maximum1 :: Ord a => Compose f g a -> a Source # minimum1 :: Ord a => Compose f g a -> a Source # maximumOn1 :: Ord b => (a -> b) -> Compose f g a -> a Source # minimumOn1 :: Ord b => (a -> b) -> Compose f g a -> a Source #

foldl1' :: (a -> a -> a) -> NonEmpty a -> a Source #

Strictly folds non-empty structure with given function f:

foldl1' f [x0, x1, x2 ...] = f (f x0 x1) x2 ...

>>> foldl1' (++) ([1,2] :| [[3,4], [5,6]])
[1,2,3,4,5,6]

Since: 0.3.0

average1 :: forall a f. (Foldable1 f, Fractional a) => f a -> a Source #

Given a Foldable1 of Fractional elements, computes the average if possible and returns the resulting element.

>>> average1 (42 :| [])
42.0
>>> average1 (1 :| [2,3,4])
2.5

Since: 1.0.0.0