The bang pattern proposal [1] still allows (!) to be used as an operator. I think there should be no difference in this regard between ! and ~, since they are used in exactly the same location. In my opinion the best thing would be to allow (~) and (@) as operators. With the same restriction on definition as (!), i.e. they must be defined in function style, not as an operator. The change to the syntax would be to remove @ and ~ from the reserved operators list [2], reservedop -> .. | : | :: | = | \ | | | <- | -> | @ | ~ | => making it reservedop -> .. | : | :: | = | \ | | | <- | -> | => Oh, and while we are at it, I think (:) should also be removed as a reservedop, there is no reason for it to be on that list. Twan [1] Bang Patterns, Haskell-prime wiki http://hackage.haskell.org/trac/haskell-prime/wiki/BangPatterns [2] Haskell 98 report, lexical structure, identifiers and operators http://haskell.org/onlinereport/lexemes.html#sect2.4