Proposal to deprecate and then drop fromJust

Joachim Breitner mail at
Tue Feb 24 10:15:25 UTC 2015


Am Dienstag, den 24.02.2015, 11:11 +0100 schrieb Henning Thielemann:
> On Mon, 23 Feb 2015, Erik de Castro Lopo wrote:
> > The idea would be to deprecate fromMaybe for 7.12 and remove it
> > completely later.
> I would deprecate it, but not remove it. Otherwise people will think that 
> this obvious function is missing by accident. We would then encounter 
> various discussions about adding it in the close future.

that’s a more useful idea, but again: Why fromJust and not head etc.?

If you would continue this thought of line towards some consistency,
then we’d need a way to annotate partial functions in general, and have
a dedicated flag -fwarn-partial-functions. (It would behave just like
deprecations – but reported separately.).  This would go well with
-fwarn-incomplete-patterns. Such a thing might be useful.


Joachim “nomeata” Breitner
  mail at joachim-breitner.de
  Jabber: nomeata at  • GPG-Key: 0xF0FBF51F
  Debian Developer: nomeata at

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