Safe Haskell | None |
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## Synopsis

- type NonNull a = [a]
- enumerate :: [a] -> [(Int, a)]
- range :: (Num a, Ord.Ord a) => a -> a -> a -> [a]
- range' :: (Num a, Ord.Ord a) => a -> a -> a -> [a]
- range_end :: (Num a, Ord.Ord a) => a -> a -> a -> [a]
- range_ :: Num a => a -> a -> [a]
- key_on :: (a -> k) -> [a] -> [(k, a)]
- key_on_snd :: (a -> k) -> [a] -> [(a, k)]
- key_on_just :: (a -> Maybe.Maybe k) -> [a] -> [(k, a)]
- first_last :: (a -> a) -> (a -> a) -> [a] -> [a]
- map_maybe_fst :: (a -> Maybe.Maybe a2) -> [(a, b)] -> [(a2, b)]
- map_maybe_snd :: (b -> Maybe.Maybe b2) -> [(a, b)] -> [(a, b2)]
- map_head :: (a -> a) -> [a] -> [a]
- map_tail :: (a -> a) -> [a] -> [a]
- map_init :: (a -> a) -> [a] -> [a]
- map_last :: (a -> a) -> [a] -> [a]
- cartesian :: [[a]] -> [[a]]
- at :: (Num i, Ord.Ord i) => [a] -> i -> Maybe.Maybe a
- insert_at :: Int -> a -> [a] -> [a]
- remove_at :: Int -> [a] -> [a]
- take_at :: Int -> [a] -> Maybe.Maybe (a, [a])
- modify_at :: Int -> (a -> a) -> [a] -> [a]
- find_modify :: (a -> Bool) -> (a -> a) -> [a] -> Maybe.Maybe [a]
- update_at :: a -> Int -> (Maybe.Maybe a -> a) -> [a] -> [a]
- move :: Int -> Int -> [a] -> Maybe.Maybe [a]
- min_on :: Ord.Ord k => (a -> k) -> a -> a -> a
- max_on :: Ord.Ord k => (a -> k) -> a -> a -> a
- minimum_on :: Ord.Ord k => (a -> k) -> [a] -> Maybe.Maybe a
- maximum_on :: Ord.Ord k => (a -> k) -> [a] -> Maybe.Maybe a
- minimum :: Ord.Ord a => [a] -> Maybe.Maybe a
- maximum :: Ord.Ord a => [a] -> Maybe.Maybe a
- ne_minimum :: Ord.Ord a => NonEmpty a -> a
- ne_maximum :: Ord.Ord a => NonEmpty a -> a
- insert_on :: Ord.Ord k => (a -> k) -> a -> [a] -> [a]
- sort_on :: Ord.Ord k => (a -> k) -> [a] -> [a]
- reverse_sort_on :: Ord.Ord b => (a -> b) -> [a] -> [a]
- merge :: Ord.Ord a => [a] -> [a] -> [a]
- merge_by :: (a -> a -> Ord.Ordering) -> [a] -> [a] -> [a]
- merge_on :: Ord.Ord k => (a -> k) -> [a] -> [a] -> [a]
- merge_lists :: Ord.Ord k => (a -> k) -> [[a]] -> [a]
- merge_asc_lists :: Ord.Ord k => (a -> k) -> [[a]] -> [a]
- group_adjacent :: Eq key => (a -> key) -> [a] -> [NonNull a]
- keyed_group_adjacent :: Eq key => (a -> key) -> [a] -> [(key, NonNull a)]
- keyed_group_sort :: Ord.Ord key => (a -> key) -> [a] -> [(key, NonNull a)]
- group_fst :: Ord.Ord a => [(a, b)] -> [(a, NonNull b)]
- group_snd :: Ord.Ord b => [(a, b)] -> [(NonNull a, b)]
- group_sort :: Ord.Ord key => (a -> key) -> [a] -> [NonNull a]
- group_stable_with :: (a -> a -> Bool) -> [a] -> [NonEmpty a]
- group_stable :: Eq key => (a -> key) -> [a] -> [NonEmpty a]
- keyed_group_stable :: Eq key => (a -> key) -> [a] -> [(key, [a])]
- zip_next :: [a] -> [(a, Maybe.Maybe a)]
- zip_nexts :: [a] -> [(a, [a])]
- zip_prev :: [a] -> [(Maybe.Maybe a, a)]
- zip_neighbors :: [a] -> [(Maybe.Maybe a, a, Maybe.Maybe a)]
- zip_remainder :: [a] -> [b] -> ([(a, b)], Either.Either [a] [b])
- data Paired a b
- paired_second :: Paired a b -> Maybe.Maybe b
- paired_first :: Paired a b -> Maybe.Maybe a
- partition_paired :: [Paired a b] -> ([a], [b])
- zip_padded :: [a] -> [b] -> [Paired a b]
- zip_padded_snd :: [a] -> [b] -> [(a, Maybe.Maybe b)]
- zipper :: [a] -> [a] -> [([a], [a])]
- equal_pairs :: (a -> b -> Bool) -> [a] -> [b] -> [Paired a b]
- indexed_pairs :: (a -> b -> Bool) -> [a] -> [b] -> [(Int, Paired a b)]
- indexed_pairs_on :: Eq k => (a -> k) -> [a] -> [a] -> [(Int, Paired a a)]
- pair_sorted :: Ord.Ord k => [(k, a)] -> [(k, b)] -> [(k, Paired a b)]
- pair_sorted_on :: Ord.Ord k => (a -> k) -> [a] -> [a] -> [Paired a a]
- pair_on :: Ord.Ord k => (a -> k) -> (b -> k) -> [a] -> [b] -> [Paired a b]
- pair_on1 :: Ord.Ord k => (a -> k) -> [a] -> [a] -> [Paired a a]
- diff :: (a -> b -> Bool) -> [a] -> [b] -> [Either.Either a b]
- partition2 :: (a -> Bool) -> (a -> Bool) -> [a] -> ([a], [a], [a])
- partition_on :: (a -> Maybe.Maybe b) -> [a] -> ([b], [a])
- chunked :: Int -> [a] -> [[a]]
- rotate :: [[a]] -> [[a]]
- rotate2 :: [[a]] -> [[Maybe.Maybe a]]
- head :: [a] -> Maybe.Maybe a
- last :: [a] -> Maybe.Maybe a
- tail :: [a] -> Maybe.Maybe [a]
- drop_dups :: Eq k => (a -> k) -> [a] -> [a]
- drop_with :: (a -> a -> Bool) -> [a] -> [a]
- partition_dups :: Ord.Ord k => (a -> k) -> [a] -> ([a], [(a, NonNull a)])
- drop_initial_dups :: Eq k => (a -> k) -> [a] -> [a]
- unique :: Ord.Ord a => [a] -> [a]
- unique_on :: Ord.Ord k => (a -> k) -> [a] -> [a]
- unique_sort :: Ord.Ord a => [a] -> [a]
- rtake :: Int -> [a] -> [a]
- rtake_while :: (a -> Bool) -> [a] -> [a]
- rdrop :: Int -> [a] -> [a]
- rdrop_while :: (a -> Bool) -> [a] -> [a]
- lstrip :: String -> String
- rstrip :: String -> String
- strip :: String -> String
- drop_prefix :: Eq a => [a] -> [a] -> ([a], Bool)
- drop_suffix :: Eq a => [a] -> [a] -> ([a], Bool)
- break_tails :: ([a] -> Bool) -> [a] -> ([a], [a])
- span_end :: (a -> Bool) -> [a] -> ([a], [a])
- span_while :: (a -> Maybe.Maybe b) -> [a] -> ([b], [a])
- span_end_while :: (a -> Maybe.Maybe b) -> [a] -> ([a], [b])
- viewr :: [a] -> Maybe.Maybe ([a], a)
- ne_viewr :: NonEmpty a -> ([a], a)
- split_before :: (a -> Bool) -> [a] -> [[a]]
- split_after :: (a -> Bool) -> [a] -> [[a]]
- split :: Eq a => NonNull a -> [a] -> NonNull [a]
- split_null :: Eq a => NonNull a -> [a] -> [[a]]
- split1 :: Eq a => NonNull a -> [a] -> ([a], [a])
- join :: Monoid a => a -> [a] -> a
- join2 :: (Monoid a, Eq a) => a -> a -> a -> a
- split_between :: (a -> a -> Bool) -> [a] -> [[a]]
- break_between :: (a -> a -> Bool) -> [a] -> ([a], [a])
- replace :: Eq a => [a] -> [a] -> [a] -> [a]
- replace1 :: Eq a => a -> [a] -> [a] -> [a]
- count :: Foldable t => (a -> Bool) -> t a -> Int
- mapAccumLM :: Monad m => (state -> x -> m (state, y)) -> state -> [x] -> m (state, [y])

# Documentation

This is just a list, but is documentation that a return value will never
be null, or an argument should never be null. This is for cases where
`NonEmpty`

is too annoying to work with.

# enumeration

range :: (Num a, Ord.Ord a) => a -> a -> a -> [a] Source #

Enumerate an inclusive range. Uses multiplication instead of successive addition to avoid loss of precision.

Also it doesn't require an Enum instance.

range_end :: (Num a, Ord.Ord a) => a -> a -> a -> [a] Source #

Like `range`

, but always includes the end, even if it doesn't line up on
a step.

# transformation

key_on_snd :: (a -> k) -> [a] -> [(a, k)] Source #

key_on_just :: (a -> Maybe.Maybe k) -> [a] -> [(k, a)] Source #

first_last :: (a -> a) -> (a -> a) -> [a] -> [a] Source #

Apply a function to the first and last elements. Middle elements are unchanged. A null or singleton list is also unchanged.

map_maybe_fst :: (a -> Maybe.Maybe a2) -> [(a, b)] -> [(a2, b)] Source #

Filter on the fst values returning Just.

map_maybe_snd :: (b -> Maybe.Maybe b2) -> [(a, b)] -> [(a, b2)] Source #

Filter on the snd values returning Just.

# permutations

cartesian :: [[a]] -> [[a]] Source #

The cartesian product of a list of lists. E.g.
`[[1, 2], [3, 4]]`

-> `[[1, 3], [1, 4], [2, 3], [2, 4]]`

.

# indexing lists

at :: (Num i, Ord.Ord i) => [a] -> i -> Maybe.Maybe a Source #

Get `xs !! n`

, but return Nothing if the index is out of range.

insert_at :: Int -> a -> [a] -> [a] Source #

Insert `x`

into `xs`

at index `i`

. If `i`

is out of range, insert at the
beginning or end of the list.

remove_at :: Int -> [a] -> [a] Source #

Remove the element at the given index. Do nothing if the index is out of range.

take_at :: Int -> [a] -> Maybe.Maybe (a, [a]) Source #

Like `remove_at`

but return the removed element as well.

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

Modify element at an index by applying a function to it. If the index is out of range, nothing happens.

find_modify :: (a -> Bool) -> (a -> a) -> [a] -> Maybe.Maybe [a] Source #

Find an element, then change it. Return Nothing if the element wasn't found.

update_at :: a -> Int -> (Maybe.Maybe a -> a) -> [a] -> [a] Source #

Similar to `modify_at`

, but will insert an element for an out of range
positive index. The list will be extended with `deflt`

, and the modify
function passed a Nothing.

move :: Int -> Int -> [a] -> Maybe.Maybe [a] Source #

Move an element from one index to another, or Nothing if the `from`

index was out of range.

# min / max

minimum_on :: Ord.Ord k => (a -> k) -> [a] -> Maybe.Maybe a Source #

maximum_on :: Ord.Ord k => (a -> k) -> [a] -> Maybe.Maybe a Source #

minimum :: Ord.Ord a => [a] -> Maybe.Maybe a Source #

maximum :: Ord.Ord a => [a] -> Maybe.Maybe a Source #

ne_minimum :: Ord.Ord a => NonEmpty a -> a Source #

ne_maximum :: Ord.Ord a => NonEmpty a -> a Source #

# ordered lists

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

Like `sort_on`

, but sort highest-to-lowest.

merge :: Ord.Ord a => [a] -> [a] -> [a] Source #

Merge sorted lists. If two elements compare equal, the one from the left list comes first.

merge_by :: (a -> a -> Ord.Ordering) -> [a] -> [a] -> [a] Source #

merge_lists :: Ord.Ord k => (a -> k) -> [[a]] -> [a] Source #

merge_asc_lists :: Ord.Ord k => (a -> k) -> [[a]] -> [a] Source #

If the heads of the sublists are also sorted I can be lazy in the list of sublists too. This version is optimized for minimal overlap.

# grouping

## adjacent

group_adjacent :: Eq key => (a -> key) -> [a] -> [NonNull a] Source #

This is just `groupBy`

except with a key function.

keyed_group_adjacent :: Eq key => (a -> key) -> [a] -> [(key, NonNull a)] Source #

Like `group_adjacent`

, but include the key.

## sort

:: Ord.Ord key | |

=> (a -> key) | |

-> [a] | |

-> [(key, NonNull a)] | Sorted by key. The NonNull group is in the same order as the input. |

Group the unsorted list into `(key x, xs)`

where all `xs`

compare equal
after `key`

is applied to them.

group_fst :: Ord.Ord a => [(a, b)] -> [(a, NonNull b)] Source #

Similar to `keyed_group_sort`

, but key on the fst element, and strip the
key out of the groups.

group_snd :: Ord.Ord b => [(a, b)] -> [(NonNull a, b)] Source #

Like `group_fst`

, but group on the snd element.

group_sort :: Ord.Ord key => (a -> key) -> [a] -> [NonNull a] Source #

Like `groupBy`

, but the list doesn't need to be sorted, and use a key
function instead of equality. The list is sorted by the key, and the groups
appear in their original order in the input list.

## stable

group_stable_with :: (a -> a -> Bool) -> [a] -> [NonEmpty a] Source #

Group each element with all the other elements that compare equal to it. The heads of the groups appear in their original order.

group_stable :: Eq key => (a -> key) -> [a] -> [NonEmpty a] Source #

`group_stable_with`

but with a key function.

keyed_group_stable :: Eq key => (a -> key) -> [a] -> [(key, [a])] Source #

# zipping

zip_next :: [a] -> [(a, Maybe.Maybe a)] Source #

Pair each element with the following element. The last element is paired
with Nothing. Like `zip xs (drop 1 xs ++ f (last xs))`

but only traverses
`xs`

once.

zip_prev :: [a] -> [(Maybe.Maybe a, a)] Source #

zip_neighbors :: [a] -> [(Maybe.Maybe a, a, Maybe.Maybe a)] Source #

Like `zip_next`

but with both preceding and following elements.

zip_remainder :: [a] -> [b] -> ([(a, b)], Either.Either [a] [b]) Source #

This is like `zip`

, but it returns the remainder of the longer argument
instead of discarding it.

paired_second :: Paired a b -> Maybe.Maybe b Source #

paired_first :: Paired a b -> Maybe.Maybe a Source #

partition_paired :: [Paired a b] -> ([a], [b]) Source #

zip_padded :: [a] -> [b] -> [Paired a b] Source #

zip_padded_snd :: [a] -> [b] -> [(a, Maybe.Maybe b)] Source #

Like `zip`

, but the second list is padded with Nothings.

zipper :: [a] -> [a] -> [([a], [a])] Source #

Return the reversed inits paired with the tails. This is like a zipper moving focus along the input list.

equal_pairs :: (a -> b -> Bool) -> [a] -> [b] -> [Paired a b] Source #

Pair `a`

elements up with `b`

elements. If they are equal according to
the function, they'll both be Both in the result. If an `a`

is deleted
going from `a`

to `b`

, it will be First, and Second for `b`

.

Kind of like an edit distance, or a diff.

indexed_pairs :: (a -> b -> Bool) -> [a] -> [b] -> [(Int, Paired a b)] Source #

This is like `equal_pairs`

, except that the index of each pair in the
*right* list is included. In other words, given `(i, Second y)`

,
`i`

is the position of `y`

in the `b`

list. Given `(i, First x)`

,
`i`

is where `x`

was deleted from the `b`

list.

pair_sorted :: Ord.Ord k => [(k, a)] -> [(k, b)] -> [(k, Paired a b)] Source #

Pair up two lists of sorted pairs by their first element.

pair_sorted_on :: Ord.Ord k => (a -> k) -> [a] -> [a] -> [Paired a a] Source #

Like `pair_sorted`

, but use a key function, and omit the extracted key.

pair_on :: Ord.Ord k => (a -> k) -> (b -> k) -> [a] -> [b] -> [Paired a b] Source #

Sort the lists on with the key functions, then pair them up.

pair_on1 :: Ord.Ord k => (a -> k) -> [a] -> [a] -> [Paired a a] Source #

Like `pair_on`

, but when the lists have the same type.

diff :: (a -> b -> Bool) -> [a] -> [b] -> [Either.Either a b] Source #

Left if the val was in the left list but not the right, Right for the converse.

# partition

partition2 :: (a -> Bool) -> (a -> Bool) -> [a] -> ([a], [a], [a]) Source #

Like `partition`

, but partition by two functions consecutively.

partition_on :: (a -> Maybe.Maybe b) -> [a] -> ([b], [a]) Source #

# sublists

rotate :: [[a]] -> [[a]] Source #

Take a list of rows to a list of columns. This is like a zip except for variable-length lists. Similar to zip, the result is trimmed to the length of the shortest row.

rotate2 :: [[a]] -> [[Maybe.Maybe a]] Source #

Similar to `rotate`

, except that the result is the length of the longest
row and missing columns are Nothing. Analogous to `zip_padded`

.

## extracting sublists

head :: [a] -> Maybe.Maybe a Source #

Total variants of unsafe list operations.

last :: [a] -> Maybe.Maybe a Source #

Total variants of unsafe list operations.

tail :: [a] -> Maybe.Maybe [a] Source #

drop_dups :: Eq k => (a -> k) -> [a] -> [a] Source #

Drop adjacent elts if they are equal after applying the key function. The first elt is kept.

drop_with :: (a -> a -> Bool) -> [a] -> [a] Source #

Filter out elts when the predicate is true for adjacent elts. The first
elt is kept, and the later ones are dropped. This is like `drop_dups`

except it can compare two elements. E.g. `drop_with (>=)`

will ensure the
sequence is increasing.

Like `drop_dups`

, but return the dropped values.

drop_initial_dups :: Eq k => (a -> k) -> [a] -> [a] Source #

Like `drop_dups`

, but keep the last adjacent equal elt instead of the
first.

unique_on :: Ord.Ord k => (a -> k) -> [a] -> [a] Source #

This is like `drop_dups`

, except that it's not limited to just adjacent
elts. The output list is in the same order as the input.

unique_sort :: Ord.Ord a => [a] -> [a] Source #

Like `unique`

, but sort the list, and should be more efficient.

rtake_while :: (a -> Bool) -> [a] -> [a] Source #

rdrop_while :: (a -> Bool) -> [a] -> [a] Source #

drop_prefix :: Eq a => [a] -> [a] -> ([a], Bool) Source #

If the list doesn't have the given prefix, return the original list and False. Otherwise, strip it off and return True.

drop_suffix :: Eq a => [a] -> [a] -> ([a], Bool) Source #

## span and break

break_tails :: ([a] -> Bool) -> [a] -> ([a], [a]) Source #

Like `break`

, but the called function has access to the entire tail.

span_while :: (a -> Maybe.Maybe b) -> [a] -> ([b], [a]) Source #

Like `span`

, but it can transform the spanned sublist.

span_end_while :: (a -> Maybe.Maybe b) -> [a] -> ([a], [b]) Source #

`span_while`

from the end of the list.

viewr :: [a] -> Maybe.Maybe ([a], a) Source #

List initial and final element, if any.

## split and join

split_before :: (a -> Bool) -> [a] -> [[a]] Source #

Split before places where the function matches.

> split_before (==1) [1,2,1] [[], [1, 2], [1]]

split_after :: (a -> Bool) -> [a] -> [[a]] Source #

Split after places where the function matches.

split :: Eq a => NonNull a -> [a] -> NonNull [a] Source #

Split `xs`

on `sep`

, dropping `sep`

from the result.

split_null :: Eq a => NonNull a -> [a] -> [[a]] Source #

Like `split`

, but it returns [] if the input was null.

join2 :: (Monoid a, Eq a) => a -> a -> a -> a Source #

Binary join, but the separator is only used if both joinees are non-empty.

split_between :: (a -> a -> Bool) -> [a] -> [[a]] Source #

Split the list on the points where the given function returns true.

This is similar to `groupBy`

, except this is defined to compare adjacent
elements. `groupBy`

actually compares to the first element of each group.
E.g. you can't group numeric runs with `groupBy (a b -> b > a+1)`

.

break_between :: (a -> a -> Bool) -> [a] -> ([a], [a]) Source #

# replace

replace1 :: Eq a => a -> [a] -> [a] -> [a] Source #

Replace occurrances of an element with zero or more other elements.

# search

# monadic

mapAccumLM :: Monad m => (state -> x -> m (state, y)) -> state -> [x] -> m (state, [y]) Source #

Like `mapAccumL`

, but monadic.