Отправлено с iPhone
Oct 7, 2010, в 21:03, Peter Wortmann
On Tue, 2010-10-05 at 17:10 -0700, Evan Laforge wrote:
+1 for something to solve the "dummy <- m; case dummy of" problem. Here are the possibilities I can think of:
Might be off-topic here, but I have wondered for a while why Haskell doesn't support something like follows:
do case (<- m) of ...
I think it'd be better to write just 'case (<- m) of', without 'do'.
With the more general rule being:
do ... e (<- m) g => ... m >>= \tmp -> e tmp g
Reasons: * "<-" is already "sugary", and the transformation is similar. Just removes the need for the user to define a throw-away name. * Better than liftMX and the Applicative operators. As shown, this is more flexible while requiring less magic operators as a bonus. Also makes more clear where the sides effects actually are. * Goes well with the spirit of getting the good parts of imperative coding where it potentially makes the code more concise. Can be abused, obviously, but I have also seen a lot of code that I feel could be written better using this.
Anything I am overlooking here? I tried to find a discussion about something like this, but didn't really know what to look for...
Greetings, Peter Wortmann
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