[Haskell-cafe] Prelude.head: empty list

[Clinton Mead]

Just thinking out loud here, but could one write their own Prelude which
just imports hiding (head), adds a new definition of head, and reexports
the lot. Then add this new Prelude higher in the search path perhaps?

On Monday, 14 March 2016, Han Joosten <han.joosten.han at gmail.com> wrote:

> Thanks all! Plenty good options, fortunately I found my bug pretty fast by
> simple code inspection :))
>
> 2016-03-12 4:28 GMT+01:00 Chris Wong <lambda.fairy at gmail.com
> <javascript:_e(%7B%7D,'cvml','lambda.fairy at gmail.com');>>:
>
>> On Sat, Mar 12, 2016 at 8:07 AM, Jonas Scholl
>> <anselm.scholl at tu-harburg.de
>> <javascript:_e(%7B%7D,'cvml','anselm.scholl at tu-harburg.de');>> wrote:
>> > You mean like this?
>> >
>> >   default-extensions:  CPP
>> >   cpp-options:
>> >
>> -Dhead=(foldr(const)(error("head:\x20\x65mpty\x20list\x20in\x20"++__FILE__++":"++show(__LINE__))).(take$1))
>>
>> That's pretty cool!
>>
>> By the way: can the (take$1) be removed? foldr should be lazy enough
>> already.
>>
>> --
>> Chris Wong (https://lambda.xyz)
>>
>> "I had not the vaguest idea what this meant and when I could not
>> remember the words, my tutor threw the book at my head, which did not
>> stimulate my intellect in any way." -- Bertrand Russell
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>
>
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