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optional

lib.lists.optional

Docs pulled from | This Revision | 10 minutes ago


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

lib.lists.optional usage example

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

Noogle detected

Aliases

Implementation

The following is the current implementation of this function.

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