diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 17 |
1 files changed, 9 insertions, 8 deletions
@@ -9033,23 +9033,24 @@ the gen-func to populate it with the first item. The giterate function is similar to generate, except that <while-fun> and <gen-fun> are functions of one argument rather than functions of no arguments. The optional <value> argument defaults to nil and -is threaded through the function calls. Prior to producing the first item, -the lazy list returned by giterate invokes <while-fun> on <value>. -If the call yields true, then <gen-fun> is invoked on <value> and the -resulting value is added to the sequence. That resulting value also becomes the -value for the next iteration: when <while-fun> is invoked again, that -value is used, rather than the original value. +is threaded through the function calls. That is to say, the lazy +list returned is (<value> [<gen-fun <value>] [<gen-fun> [<gen-fun> <value>]] ...). + +The lazy list terminates when a value fails to satsify <while-fun>. +That is to say, prior to generating each value, the lazy list tests +the value using <while-fun>. If that function returns false, then +the item is not added, and the sequence terminates. Note: the giterate function could be written in terms of generate like this: (defun giterate (w g v) - (generate (lambda () [w v]) (lambda () (set v [g v])))) + (generate (lambda () [w v]) (lambda () (prog1 v (set v [g v]))))) .SS Example: - (giterate (op > 5) (op + 1) 0) -> (1 2 3 4 5) + (giterate (op > 5) (op + 1) 0) -> (0 1 2 3 4) .SS Function repeat |