On Jun 21, 2012, at 1:34 AM, Robby Findler wrote: > I usually in-naturals and zero? to do this.
Ah! That's nice. I can use that. > > I see that one example (that I didn't write is in base-render.rkt > > (define/public (render-nested-flow i part ri starting-item?) > (for/list ([b (in-list (nested-flow-blocks i))] > [pos (in-naturals)]) > (render-block b part ri (and starting-item? (zero? pos))))) > > Robby > > On Thu, Jun 21, 2012 at 3:24 AM, Eli Barzilay <e...@barzilay.org> wrote: >> An hour and a half ago, John Clements wrote: >>> 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>]) …) >> >> What are you using it for? (Out of curiosity, I wonder if there's any >> need for this that doesn't fall under what `add-between' does.) Nothing unusual; I'm writing newlines in between rendered expressions in the stepper. I don't think an add-between would make for more readable code in this case, but it's a related use. John
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