Re: [Chicken-hackers] substring function and bounds checks

[Michele La Monaca]

On Wed, Feb 6, 2013 at 12:47 AM, Felix
<address@hidden> wrote:
>> # perl -e 'print substr("ciao",0,10);'
>> ciao
>> # ruby -e 'puts "ciao"[0..10]'
>> ciao
>> # python -c 'print "ciao"[0:10];'
>> ciao
>> # csi -e '(print (substring "ciao" 0 10))'
>> Error: (substring) out of range 0 10
>>
>>         Call history:
>>
>>         <syntax>          (print (substring "ciao" 0 10))
>>         <syntax>          (substring "ciao" 0 10)
>>         <eval>    (print (substring "ciao" 0 10))
>>         <eval>    (substring "ciao" 0 10)       <--
>>
>
> The string is shorter than the limit you gave to "substring"
> in the third argument. Of course you know that, but why did
> you pass an incorrect length in the first place?
>
> This looks like it does what you want:
>
> csi -e '(print (substring "ciao" 0))'

Well, no. I was looking for a python-like substring function. Anyway,
thanks for the (substring "ciao" 0) trick, it is a very handy method
to trim strings on the left (not documented in the wiki, btw):

(substring "ciao" 1) => "iao"

In my ideal world, there would room also for that:

(substring "ciao" 0 -1) => "cia"

but I know, I know... it will never happen :-(

Regards,
Michele