[erlang-questions] Offset calculation in bit syntax

[Ben Hood]

 > There is bug in your code I think.
 >
 > Correct code should be:
 >
 > decode(<<L:8/unsigned, R/binary>>) ->
 > Len = (L - 16#20)*8,
 > <<Rest:Len/unsigned, _/binary>> = R,
 > Rest.

That's how I ended solving it, but there was also a bug in the way I  
specified the problem, what I was attempting to ask was whether  
something this was possible:

decode(<<L:8,Bin:(L - 16#20)/binary,Rest/binary>>) -> Bin.

So decode(<<16#23,"abcdefg">>) would return <<"abc">>.

Essentially this is the same thing as your solution, only expressed in  
a more compact format. However, it doesn't appear to be a legal  
operation in Erlang bit syntax. 
  
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