HELP ALLBUTCUT                                      Steve Leach     Nov 99

allbutcut( A, B, S:seq ) -> T:seq

This procedure returns a sequence with the A'th to B'th elements
removed.  It takes a pair of indices A and B and a sequence S and
returns a sequence of the same type T.  A sequence is any word
list or vectorclass object, such as a string or a vector.

The name "allbutcut" comes from the fact that it is a kind of
inverse to the "cut" procedure.  "Cut" returns the subsequence
from the A'th to B'th element whereas "allbutcut" chops them
out.  (Note that you can use HELP * SPLICE to put T back where 
you found it!)

For example

    : allbutcut( 2, 3, [ a b c d e ] ) =>
    ** [a d e]
    : allbutcut( 5, 7, 'alpha beta' ) =>
    ** alpheta
    : allbutcut( 1, 3, { foo bar gort trog } ) =>
    ** {foo bar gort}


Just as in HELP * CUT, a special feature is that A and B may be 
negative, representing indexes from the END of the sequence.  i.e. -1 
is the last element, -2 is the second to last element, and so on up 
to -length( S ) which is the first element!  (This handy idiom is 
adapted from the language Python, incidentally.)  

To learn more about the range of indices allowed, you should
read the details in HELP * CUT.

Here are some examples :-

    : allbutcut( 2, -1, [ a b c d e ] ) =>
    ** [a]
    : allbutcut( 5, -2, 'alpha beta' ) =>
    ** alpha
    : allbutcut( 1, -3, { foo bar gort trog } ) =>
    ** {gort trog}

Lastly, A or B can be <false>.  They default to 1 and -1
respectively.

    : allbutcut( 2, false, [ a b c d e ] ) =>
    ** [a]
    : allbutcut( false, false, 'alpha beta' ) =>
    **
    : allbutcut( false, -3, { foo bar gort trog } ) =>
    ** {gort trog}


Expert programmers should note that -allbutcut- does not always return a
copy.  In fact it often returns a shared object.


-- See Also -------------------------------------------------------------

HELP * ALLBUTFIRST
HELP * ALLBUTLAST
HELP * CUT
HELP * SPLICE
HELP * SUBSTRING