group package:relude

group :: Eq a => [a] -> [[a]]
relude Relude.List.Reexport
The group function takes a list and returns a list of lists such that the concatenation of the result is equal to the argument. Moreover, each sublist in the result is non-empty and all elements are equal to the first one. group is a special case of groupBy, which allows the programmer to supply their own equality test. It's often preferable to use Data.List.NonEmpty.group, which provides type-level guarantees of non-emptiness of inner lists.

Examples

>>> group "Mississippi"
["M","i","ss","i","ss","i","pp","i"]

>>> group [1, 1, 1, 2, 2, 3, 4, 5, 5]
[[1,1,1],[2,2],[3],[4],[5,5]]
module Relude.Extra.Group
relude
Polymorphic grouping functions.
groupBy :: (Foldable f, DynamicMap t, Val t ~ NonEmpty a, Monoid t) => (a -> Key t) -> f a -> t
relude Relude.Extra.Group
Groups elements using results of the given function as keys. 
>>> groupBy even [1..6] :: HashMap Bool (NonEmpty Int)
fromList [(False,5 :| [3,1]),(True,6 :| [4,2])]
groupOneBy :: (Foldable f, DynamicMap t, Val t ~ a, Monoid t) => (a -> Key t) -> f a -> t
relude Relude.Extra.Group
Similar to groupBy but keeps only one element as value. 
>>> groupOneBy even [1 .. 6] :: HashMap Bool Int
fromList [(False,1),(True,2)]
class Semigroup a
relude Relude.Monoid
The class of semigroups (types with an associative binary operation). Instances should satisfy the following:
  • Associativity x <> (y <> z) = (x <> y) <> z
You can alternatively define sconcat instead of (<>), in which case the laws are: