Isaac Dupree
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)}