Reality check before I do something dumb and re-invent the wheel: I often want to write a for loop where the first element is treated specially. In such cases, it would be nice to have a sequence that had a #t and then an infinite number of #f's, so I could write
(for ([s my-sequence] [first? <true-then-always-falses>]) …) Hey, no problem! Mutable lists can be used as sequences. But--and here I feel as though my brains have suddenly vanished--I can't think of the nice short way to write (mlist #t #f …) I'd be sort of okay with writing (mcons #t #0=(mcons #f #0#)) … but that's not allowed, either. Yes, of course I can do it the ugly way: (define p1 (mcons #f 'bogus)) (set-mcdr! p1 p1) (define true-then-falses (mcons #t p1)) Of course, it would be unbelievably easy to write an mlist syntactic form, but there *must* be a form that's been around for 150 years that already does this. Sorry to have forgotten Scheme, John
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