[Haskell-beginners] comment on this debugging trick?

[Dennis Raddle]

On Fri, Nov 27, 2015 at 10:31 AM, Jeffrey Brown <jeffbrown.the at gmail.com>
wrote:

> Elliot Cameron, very smart guy, once advised me to make illegal state
> invalid. Jake Brownson, another, recommended trying to use Maybes and
> Eithers instead of throwing exceptions. I'm having trouble coming up with
> examples but I think they're both helpful.
>
>
I think I know roughly what you are talking about, but there are places
where unexpected input might result in something like an empty list.
Suppose I need the head of that list under normal conditions. Maybe the
list is produced by library code so I can't alter the data structures.
That's the kind of situation I want to identify precisely and immediately.

D
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