Am Montag 11 Januar 2010 05:08:30 schrieb Dmitry Tsygankov:
2010/1/10 Yitzchak Gale
IMHO, the monomorphism restriction does not make sense at the GHCi prompt in any case, no matter what you have or haven't loaded, and no matter what your opinion of MR in general.
Looks reasonable to me, that's why I intuitively expected let q = fmap MovieLister createFinder to work. Not sure I would want that behaviour when I ':load' a file though, as it may provide a false sense of security. -XTypeFamilies isn't turned on automatically, why should -XNoMonomorphismRestriction be?
You're more likely to omit (forget) type signatures for quick bindings at the prompt. The monomorphism restriction is inconvenient then.
I recommend that you create a file called ".ghci"
in your home directory, and put into it the line: :set -XNoMonomorphismRestriction
That seems to also affect how the file is ':load'-ed, not sure I would want to do that.
If you want the MR in some module, you can enable it via {-# LANGUAGE MonomorphismRestriction #-} there. It's a question of what you deem more (in)convenient. Since the MR is not entirely unlikely to be removed from the (default) language, the latter is more future-proof.