[Haskell-cafe] data.binary get reading beyond end of input
conrad at metadecks.org
Thu Jul 29 06:17:57 EDT 2010
On 29 July 2010 19:13, Duncan Coutts <duncan.coutts at googlemail.com> wrote:
> On Thu, 2010-07-29 at 19:01 +0900, Conrad Parker wrote:
>> On 29 July 2010 17:46, Duncan Coutts <duncan.coutts at googlemail.com> wrote:
>> > On 29 July 2010 07:53, Conrad Parker <conrad at metadecks.org> wrote:
>> >>> Something smells fishy here. I have a hard time believing that binary is
>> >>> reading more input than is available? Could you post more code please?
>> >> The issue seems to just be the return value for "bytes consumed" from
>> >> getLazyByteString. Here's a small example.
>> > http://hackage.haskell.org/packages/archive/binary/0.5.0.2/doc/html/Data-Binary-Get.html#v%3AgetLazyByteString
>> > getLazyByteString :: Int64 -> Get ByteString
>> > An efficient get method for lazy ByteStrings. Does not fail if fewer
>> > than n bytes are left in the input.
>> > Because it does it lazily it cannot check if it's gone past the end of
>> > the input. Arguably this is crazy and the function should not exist.
>> cheers Duncan, that confirms my guess about the reason. Would you
>> accept a patch quoting you on that last point to the comment? ;-)
> The consensus plan amongst the binary hackers is to eliminate lazy
> lookahead functions and to rebuild binary on top of a continuation style
> using strict chunks (then with lazy decoding built on top).
I'll take that as a no on the patch.
How would that plan differ from having an iteratee version of
data.binary? ie. something that is easily compatible with
WrappedByteString, as the existing Data.Binary is easily compatible
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