[erlang-questions] Bit String Comprehension Question

Grasl Christoph <>
Tue Sep 9 18:22:40 CEST 2008


sorry, however, for the noize dear david,

you need to declare that's a bitstring, 
binaries is default and therefore the expected type, 
so this will work 4 u:

<< <<Bin/bitstring>> || Bin <- [<<3:5>>] >>.

it's well explained in the documentation ('programming-examples/constructing binaries and bitstrings')..

Cheers,

Christoph Grasl
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-----Ursprüngliche Nachricht-----
Von: David Mercer [mailto:]
Gesendet: Di 09.09.2008 17:52
An: Grasl Christoph; 
Betreff: RE: [erlang-questions] Bit String Comprehension Question
 
My question, however, is regarding bit string comprehension, not list
comprehension.  Please advise.  Thank-you.

> -----Original Message-----
> From: Grasl Christoph [mailto:]
> Sent: Tuesday, September 09, 2008 09:55
> To: ; 
> Subject: AW: [erlang-questions] Bit String Comprehension Question
> 
> Dear, David
> 
> [Bin || Bin <- [<<3:5>>] ].
> 
> works fine..
> 
> the syntactical notation for a list comprehension needs to be in '[' & ]'
> whereas you have used the binary/bitstring syntax to 'bracket' your
> comprehension
> together with the '||', which is typically a list-comp.
> could be mistaken, but it looks like u'r mixing up to notations..
> 
> Cheers,
> 
> Christoph Grasl
> Embedded Software Entwickler
> 
> KEYTRONIX
> Gesellschaft für industrielle Elektronik und Informationstechnologie mbH
> 
> Ungargasse 64-66/1/109
> A-1030 WIEN
> 
> E-Mail: 
> Tel.: +43 (1) 718 06 60 - 323
> Mobil: +43 (664) 8556456
> WWW: http://www.keytronix.com
> 
> HG Wien FN 261131t
> 
> Confidentiality Notice:
> This message may contain privileged and confidential information. If you
> think, for any reason, that this message may have been addressed to you in
> error, you must not disseminate, copy or take any action in reliance on
> it, and we would ask you to notify us immediately by return email.
> 
> 
> 
> -----Ursprüngliche Nachricht-----
> Von:  im Auftrag von David Mercer
> Gesendet: Di 09.09.2008 16:18
> An: 'erlang-questions'
> Betreff: [erlang-questions] Bit String Comprehension Question
> 
> Why does the bit-string comprehension #133 below work whereas #134 is a
> syntax error?
> 
> 
> 
> 133> << <<X:N>> || {X,N} <- [{3,5}] >>.
> 
> 
> <<3:5>>
> 
> 134> << Bin || Bin <- [<<3:5>>] >>.
> 
> * 1: syntax error before: '||'
> 
> 
> 
> Please advise.  Thank-you.
> 
> 
> 
> David Mercer
> 
> 
> 
> 
> 



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