[Haskell-cafe] ANNOUNCE: vector-bytestring-

Roman Leshchinskiy rl at cse.unsw.edu.au
Wed Oct 19 21:22:41 CEST 2011

Ivan Lazar Miljenovic wrote:
> On 19 October 2011 22:09, Roman Leshchinskiy <rl at cse.unsw.edu.au> wrote:
>> So it seems that (1) people have very different requirements and (2) the
>> Show instance only really matters for debugging in ghci. Here is a
>> thought. What if ghci allowed Show instances to be overridden
>> dynamically?
>> So you could put your preferred Show instance for Vector Word8 in you
>> .ghci file and ghci would use that when displaying stuff (but not when
>> actually evaluating things). Would that solve most of the problems
>> without
>> messing with vector's Show instances?
> Would this hypothetical ghci feature also work for cases where you
> have a ByteString as part of another type that derives Show and Read?

Yes. The idea would be to evaluate the expression, then build the Show
instance for the type of the result taking the ghci overrides into account
and then use that to display the result. I have to admit that I have no
idea how difficult it would be to do this but surely it can't be that


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