[erlang-questions] Element Typing in Record Declarations?

David Mercer <>
Wed Feb 25 21:47:07 CET 2009


Hadn't noticed that syntax.  Thank-you.  Am replacing:

	-type bitstring() :: any().

with:

	-type bitstring() :: <<_:_*1>>.

> -----Original Message-----
> From: Per Gustafsson [mailto:]
> Sent: Wednesday, February 25, 2009 2:15 PM
> To: David Mercer
> Cc: 'Kostis Sagonas'; 
> Subject: Re: [erlang-questions] Element Typing in Record Declarations?
> 
> David Mercer wrote:
> > Are there any plans to add bitstrings as a type?  Currently, these have
> to
> > be defined as any(), since binary() implies that bit_size is a multiple
> of
> > 8.
> >
> >
> 
> You should be able to write:
> 
> <<_:_*1>> for a bitstring or more generally:
> <<_:M, _:_*N>> for a bitsring consisting of M+X*N bits where M, X and N
> are non-negative integers.
> 
> Per
> 
> >> -----Original Message-----
> >> From:  [mailto:erlang-questions-
> >> ] On Behalf Of Kostis Sagonas
> >> Sent: Tuesday, February 24, 2009 9:33 AM
> >> To: 
> >> Subject: Re: [erlang-questions] Element Typing in Record Declarations?
> >>
> >> David Mercer wrote:
> >>
> >>> I just noticed in dict.erl:
> >>>
> >>> ...
> >>>
> >>> It appears that Erlang supports type declarations in record
> >>> declarations, but I could not find this syntax in the Erlang reference
> >>> documentation.  Is there any documentation on this, and what effect it
> >>> has on the system?
> >>>
> >> The documentation on this is currently an EEP:
> >>
> >> 	http://www.erlang.org/eeps/eep-0008.html
> >>
> >> This type information is used by Dialyzer to detect discrepancies
> >> between the declared types of record fields and their actual uses.
> >>
> >> Kostis
> >> _______________________________________________
> >> erlang-questions mailing list
> >> 
> >> http://www.erlang.org/mailman/listinfo/erlang-questions
> >>
> >
> > _______________________________________________
> > erlang-questions mailing list
> > 
> > http://www.erlang.org/mailman/listinfo/erlang-questions
> >




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