[Haskell-cafe] YAWQ (Yet Another Wash Question)

[Mike Gunter]

The most natural seeming thing is one permutation you don't mention:

         do x <- if cond then Just $ textInputField ...
                         else return Nothing
         ...
	 ... submit ... -- perhaps: maybe (return ()) submit x
			-- or       submit (fromMaybe <something> x)

.  Does that do what you want?

	mike


John Goerzen <jgoerzen at complete.org> writes:

> Thanks for everyone that's helped me out with my Wash questions.  I have
> one more.
>
> I have a textInputField that I only want to display on a form in certain
> cituations.  I can't figure out how to make this work.  For instance:
>
> ... do if cond
>           then x <- textInputField ...
>           else ()
>        ...
>        submit ...
>
> Well, two problems there... first, the scope of the x doesn't reach to
> the submit.  Second, there's a type issue.  So I thought maybe I could
> figure out something like this:
>
> ... do x <- if cond
>                then textInputField ...
>                else ()
>
> still stuck with the typing problem.
>
> So I thought maybe something like this...
>
> ... do let x = if cond
>                   then Just $ textInputField ...
>                   else Nothing
>
> Though I suspect this won't work either, since the textInputField won't
> actually be processed at the right place in the program.
>
> I then thought maybe I could kludge by this with a hidden field, but I
> can't find one of those, either.
>
> Ideas, anyone?
>
> Thanks,
> John
>
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