I am not sure what a "boolean list for the first number" is,
but:
(~: {. >:@}:@, ]) 4 5 6 7 8 11 12 16 17 19 21
1 0 0 0 0 1 0 1 0 1 1
(~: {. >:@}:@, ]) 0$0
The pattern learned in APL in ancient days, is:
instead of doing (}.y) f (}:y) , do y f }:blah,y
for some suitable blah.
----- Original Message -----
From: bill lam <bbill....@gmail.com>
Date: Sunday, April 26, 2009 22:40
Subject: [Jprogramming] first stone
To: JProgramming <programming@jsoftware.com>
> I try to find the boolean list for the first number in an strictly
> increasing integer list. eg.
>
> 1, ( >:@}: ~: }.) 4 5 6 7 8 11 12 16 17 19 21
> 1 0 0 0 0 1 0 1 0 1 1
>
> but it does not handle the corner case where the list is empty
>
> 1, ( >:@}: ~: }.) 0$0
> 1
>
> I want it to return an empty list instead. Any idea?
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