:: Maybe a -> [a] package:rio

The maybeToList function returns an empty list when given Nothing or a singleton list when given Just.

Examples

Basic usage:

>>> maybeToList (Just 7)
[7]

>>> maybeToList Nothing
[]

One can use maybeToList to avoid pattern matching when combined with a function that (safely) works on lists:

>>> import Text.Read ( readMaybe )

>>> sum $ maybeToList (readMaybe "3")
3

>>> sum $ maybeToList (readMaybe "")
0

List of elements of a structure, from left to right.

O(n) Convert a vector to a list

O(n) Convert different vector types

O(1) First element of a vector in a monad. See indexM for an explanation of why this is useful.

O(1) Last element of a vector in a monad. See indexM for an explanation of why this is useful.

O(1) First element in a monad without checking for empty vectors. See indexM for an explanation of why this is useful.

O(1) Last element in a monad without checking for empty vectors. See indexM for an explanation of why this is useful.