On Sat, Dec 08, 2007 at 03:28:58PM -0200, Felipe Lessa wrote:
> On Dec 8, 2007 3:12 PM, Ilya Tsindlekht <[EMAIL PROTECTED]> wrote:
> > On Sat, Dec 08, 2007 at 02:59:16PM -0200, Felipe Lessa wrote:
> > > Prelude> do {1 <- return 3; return' "ok"}
> > > Nothing
> > > Prelude> return 3 >>= \1 -> return' "ok"
> > > *** Exception: <interactive>:1:13-30: Non-exhaustive patterns in lambda
> > What seems confusing to you?
> >
> > \1 -> foo
> > is the same as
> > \x -> case x of {1 -> foo;}
> >
> > When this function is evaluated with parameter different from 1, Haskell
> > fails to find matching pattern for x and exception occurs.
>
> The problem is that with the do notation it doesn't raise an
> exception. In the example you quoted,
Yes, I have already understood it from your reply to the original
poster.
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