lib.lists.optional

Return a singleton list or an empty list, depending on a boolean value. Useful when building lists with optional elements (e.g. ++ optional (system == "i686-linux") firefox).

Inputs

cond

1. Function argument

elem

2. Function argument

Type

optional :: bool -> a -> [a]

Examples

optional true "foo"
=> [ "foo" ]
optional false "foo"
=> [ ]

Noogle detected

• lib.optional

optional = cond: elem: if cond then [ elem ] else [ ];