Int -> [a] -> [[a]] -text
drop n xs returns the suffix of xs after the first n elements, or [] if n > length xs:
> drop 6 "Hello World!" == "World!"
> drop 3 [1,2,3,4,5] == [4,5]
> drop 3 [1,2] == []
> drop 3 [] == []
> drop (-1) [1,2] == [1,2]
> drop 0 [1,2] == [1,2]
It is an instance of the more general Data.List.genericDrop, in which n may be of any integral type.
take n, applied to a list xs, returns the prefix of xs of length n, or xs itself if n > length xs:
> take 5 "Hello World!" == "Hello"
> take 3 [1,2,3,4,5] == [1,2,3]
> take 3 [1,2] == [1,2]
> take 3 [] == []
> take (-1) [1,2] == []
> take 0 [1,2] == []
It is an instance of the more general Data.List.genericTake, in which n may be of any integral type.
replicateM n act performs the action n times, gathering the results.
The intersperse function takes an element and a list and `intersperses' that element between the elements of the list. For example,
> intersperse ',' "abcde" == "a,b,c,d,e"
replicate n x is a list of length n with x the value of every element. It is an instance of the more general Data.List.genericReplicate, in which n may be of any integral type.
The non-overloaded version of insert.
The deleteBy function behaves like delete, but takes a user-supplied equality predicate.
The genericDrop function is an overloaded version of drop, which accepts any Integral value as the number of elements to drop.
The genericTake function is an overloaded version of take, which accepts any Integral value as the number of elements to take.
Append two lists, i.e.,
> [x1, ..., xm] ++ [y1, ..., yn] == [x1, ..., xm, y1, ..., yn]
> [x1, ..., xm] ++ [y1, ...] == [x1, ..., xm, y1, ...]
If the first list is not finite, the result is the first list.
The deleteFirstsBy function takes a predicate and two lists and returns the first list with the first occurrence of each element of the second list removed.
The unionBy function is the non-overloaded version of union.
scanl is similar to foldl, but returns a list of successive reduced values from the left:
> scanl f z [x1, x2, ...] == [z, z `f` x1, (z `f` x1) `f` x2, ...]
Note that
> last (scanl f z xs) == foldl f z xs.
The insert function takes an element and a list and inserts the element into the list at the last position or equal to the next element. In particular, if the list is sorted before the call, the result will also be sorted. It is a special case of insertBy, which allows the programmer to supply their own comparison function.
delete x removes the first occurrence of x from its list argument. For example,
> delete 'a' "banana" == "bnana"
It is a special case of deleteBy, which allows the programmer to supply their own equality test.
scanr is the right-to-left dual of scanl. Note that
> head (scanr f z xs) == foldr f z xs.
intercalate xs xss is equivalent to (concat (intersperse xs xss)). It inserts the list xs in between the lists in xss and concatenates the result.
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