allowing functions to treat nil arguments as empty versions of their expected types
For example:
(cons some-value my-list)
If my-list is nil, then the above expression will result in a list containing only the element some-value. Otherwise it will be a list starting with some-value followed by any other values that have been previously in my-list.
alt Hacker News
For example:
(cons some-value my-list)
If my-list is nil, then the above expression will result in a list containing only the element some-value. Otherwise it will be a list starting with some-value followed by any other values that have been previously in my-list.