behaviour change in getDirectoryContents in GHC 7.2?

Simon Marlow marlowsd at
Tue Nov 8 12:43:31 CET 2011

On 02/11/2011 21:40, Max Bolingbroke wrote:
> On 2 November 2011 20:16, Ian Lynagh<igloo at>  wrote:
>> Are you saying there's a bug that should be fixed?
> You can choose between two options:
>   1. Failing to roundtrip some strings (in our case, those containing
> the 0xEFNN byte sequences)
>   2. Having GHC's decoding functions return strings including
> codepoints that should not be allowed (i.e. lone surrogates)
> At the time I implemented this there was significant support for 2, so
> that is what we have.

Don't you mean 1 is what we have?

 > At the time I was convinced that 2 was the right
> thing to do, but now I'm more agnostic. But anyway the current
> behaviour is not really a bug -- it is by design :-)

Failing to roundtrip in some cases, and doing so silently, seems highly 
suboptimal to me.  I'm sorry I didn't pick up on this at the time 
(Unicode is a swamp :).


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