Re: Proposal to deprecate and then drop fromJust

I'm strongly in favor of removing this so as not to confuse new people with partial functions that have impossible type signatures. +1 On 02/23/2015 11:49 PM, Ivan Lazar Miljenovic wrote:

On 24 February 2015 at 16:42, Erik de Castro Lopo wrote:

...

Hi all,

We currently have in the Data.Maybe module from base:

fromJust :: Maybe a -> a

which newbies often find using hoogle or other search tools and is a huge trap. *Every* usage of the above can be replaced by using

fromMaybe :: a -> Maybe a -> a

which forces the user to provide a default value for the case where the Maybe a is a Nothing.

The idea would be to deprecate fromMaybe for 7.12 and remove it completely later.

Comments? I've used fromJust in the past when I knew the value would be Just by construction.

That said, I could always have written my own fromJust function with a custom error message, and did switch some of them to direct pattern matches (so that at least the error message said *where* the error occurred).

So I'm undecided; maybe (no pun intended!) -0.1.

...

Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/ _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries