Hello *, As you may be aware, GHC 7.10.1 updated its Unicode catalog to version 7.0, thereby causing some subscript symbols to change character properties, thereby causing GHC 7.10.1 to reject some Unicode-subscript characters that GHC 7.8.4 accepted. See https://ghc.haskell.org/trac/ghc/ticket/10196 for specific examples. In order to address this regression, one suggestion is to allow characters in the 'Letter, Modifier' category[1] from the 2nd position on in an identifier. This however may do more than just fix the regression, as it looks from [1] that it would allow many more new identifiers than were previously possible. So, is allowing 'Lm'-chars the the 2nd+ characters in an identifier a sensible change for addressing #10196 or not. If it's a bad idea, are there other suggestions worth considering? [1]: http://www.fileformat.info/info/unicode/category/Lm/list.htm Cheers, hvr