with
with — traverses an array or list performing a statement.
Syntax
with symbol in|on s_exp do statement
with symbol1 in|on s_exp symbol2 = collect|tcollect statement
Arguments
- symbol
- Any Gamma or Lisp symbol.
- s_exp
- Any Gamma or Lisp expression.
- statement
- Any statement.
Returns
nil when using the
do option, and the result of the
statement when using the
collect or tcollect
option.
Description
with
symbol in|on s_exp
do statement
- A with loop using the iteration style
in traverses an array or list as defined by
an expression (s-exp), performing the
statement with the iteration
symbol assigned to each element of the
array or list in turn.
- A with loop using the iteration style
on traverses a list defined by an expression
(s-exp), performing the
statement with the iteration
symbol assigned to the car and then
successive cdrs of the list.
- The iteration symbol is local in
scope to the with statement.
with symbol1 in|on s_exp symbol2 = collect|tcollect statement
- A with loop using the
collect directive will collect the
results of the statement for
each iteration, and produce an array or list (depending on
the type of the original array or list), whose elements
correspond on a one-to-one basis with the elements of the
original array or list.
- A with loop using the
tcollect directive will collect the results
of the statement at each iteration,
ignoring nil results in the body. The
resulting array or list will not have a one-to-one
correspondence with the original array or list.
- The result of a with loop using
collect or tcollect will be
assigned to
symbol2, which
is not local in scope to the with
statement. The iteration
symbol1 is local
in scope to the with statement.
Examples
Gamma> A = array(1,2,3,4);
[1 2 3 4]
Gamma> with x in A do
{
x = x + 1;
princ(x, "\n");
}
2
3
4
5
nil
Gamma>
Gamma> L = list (1, 2, 3, 4, 5, 6);
(1 2 3 4 5 6)
Gamma> with x on L do (princ(x,"\n"));
(1 2 3 4 5 6)
(2 3 4 5 6)
(3 4 5 6)
(4 5 6)
(5 6)
(6)
nil
nil
Gamma> with x in L y = collect x + 2;
(3 4 5 6 7 8)
Gamma> y;
(3 4 5 6 7 8)
Gamma> with x in L y = tcollect x < 4 ? x : nil;
(1 2 3)
Gamma> y;
(1 2 3)
Gamma>
