[Haskell-cafe] Crash in Data.ByteString.Lazy.hPut

[Jamie Love]

Just to clarify, I know it was my mistake, and so I'm not blaming 
Haskell or Ghc. The first few times you realise the compiler isn't a 
magic wand that stops you being silly are the hardest.

Jamie Love wrote:
> Oh, I see
>
> I wasn't thinking through the code (and I'm still in the honeymoon 
> phase with Haskell, thinking it can do no wrong).
>
> Don Stewart wrote:
>> jamie.love:
>>   
>>>    Ah, of course.
>>>
>>>    Thanks. I removed the hPut and it runs smoothly.  I had forgotten that
>>>    haskell chooses the types dynamically.
>>>
>>>    Shouldn't haskell pick up that there is no 'mod' for Word8?  I mean,
>>>    shouldn't I get a nicer error message?
>>>     
>>
>> Well, it inferred Word8 for your generated values, so 256 overflowed to 0.
>> Stating the expected type here would prevent that. (And is why mandatory 
>> top level declarations are good -- they can prevent bugs caused by 
>> an unexpected type being inferred).
>>     



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