[Haskell-cafe] Re: Debugging partial functions by the rules

[Lennart Augustsson]

Should Haskell also provide unrestricted side effects, setjmp/ 
longjmp, missile launching functions, etc?  After all, people who  
don't want to use them can just avoid them. :)


On Nov 15, 2006, at 05:07 , Neil Mitchell wrote:

> Hi
>
>> Yes, these techniques are fairly well known now, and hopefully  
>> some of
>> the more experienced Haskellers are using them (I certainly use the
>> non-empty list tricks). Any anyone with more than 6 months Haskell  
>> knows
>> to avoid fromJust.
>
> I'm not, I use fromJust all the time. Ditto for head, init,  
> maximum, foldr1...
>
>> One solution would be to deprecate fromJust (we recently decided  
>> not to
>> add fromLeft/Right for the same reasons). Having a compiler  
>> warning is a
>> good way to encourage good behaviour :)
>
> We didn't decide not to add fromLeft/fromRight, Russell decided to
> defer it to a later patch. I am still very interested in them being
> put in!
>
> There seem to be two sides forming to this issue - use partial
> functions or don't. I don't see why we should restrict the functions
> available to the partial people, when the unpartial people can choose
> not to use them.
>
> Thanks
>
> Neil
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