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All this fuss over liftA2 ?

For a monad, is liftA2 the same as l1 or l2?

  l1,l2 :: Monad m => (a -> b -> c) -> m a -> m b -> m c

  l1 fn = \ma mb -> do
    a <- ma
    b <- mb
    return fn a b

  l2 fn = \ma mb -> do
    b <- mb
    a <- ma
    return fn a b

It has to be one of the two, but which one?  This depends on the
definition of <*> for a monad.

in [1] the liftM2 operation is defined with the same type.  Is liftM2
the same as liftA2?  It has to be..

[1] http://haskell.org/ghc/docs/latest/html/libraries/base/Control-Monad.html#v:ap



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