chickadee » srfi-1 » drop-right

take-right returns the last I elements of FLIST. drop-right returns all but the last I elements of FLIST.

(take-right '(a b c d e) 2) => (d e)
(drop-right '(a b c d e) 2) => (a b c)

The returned list may share a common tail with the argument list.

FLIST may be any finite list, either proper or dotted:

(take-right '(1 2 3 . d) 2) => (2 3 . d)
(drop-right '(1 2 3 . d) 2) => (1)
(take-right '(1 2 3 . d) 0) => d
(drop-right '(1 2 3 . d) 0) => (1 2 3)

For a legal I, take-right and drop-right partition the list in a manner which can be inverted with append:

(append (take FLIST I) (drop FLIST I)) = FLIST

take-right's return value is guaranteed to share a common tail with FLIST. If the argument is a list of non-zero length, drop-right is guaranteed to return a freshly-allocated list, even in the case where nothing is dropped, e.g. (drop-right lis 0).