Isaac Dupree <[EMAIL PROTECTED]> wrote:
>
> Adde wrote:
> > tmp <- foo
> > return Bar {
> > barFoo = tmp
> > }
>
> There is a feature being worked on in GHC HEAD that would let you do
>
> do
> tmp <- foo
> return Bar{..}
>
> which captures fields from everything of the same name that's in scope.
> I think this would also satisfy your desire.
>
I guess this means I could write:
data D = C {field1 :: Bool, field2 :: Char}
f x = do
field1 <- foo1
field2 <- foo2
field3 <- foo3
other stuff
return C{..}
instead of
f x = do
tmp1 <- foo1
tmp2 <- foo2
field3 <- foo3
other stuff
return $ C { field1 = tmp1, field2 = tmp2 }
This has a dangerous feel to it ---
extending the definition of D to include a field field3
may have quite unintended consequences.
What I am missing most in the record arena
is a functional notation for record update, for example:
{^ field1 } = \ f r -> r {field1 = f (field1 r)}
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