[Haskell-cafe] Field updates in a state monad

Michael Roth mroth at nessie.de
Thu Jan 10 10:01:54 EST 2008

Hello list,

still playing with monads and states, I have the following question:


	import Control.Monad.State.Lazy

	data MyData = MyData { content :: String }

	foobar :: State MyData String
	foobar = do
	  gets content

Ok, that looks nice and tidy. But:

	foobar2 :: State MyData ()
	foobar2 = do
	  modify $ \x -> x { content = "hello haskell"}

...looks not so nice.

Exists there a way to write this cleaner without writing countless
"set_xyz" helper functions?


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