#10583: Chaos in Lexeme.hs -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: 10582 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by ezyang): Hello Richard, If you look at the types and the use-sites of the functions in question, you can get a clue what they are used for. * `isLexVarSym` operates on `FastString`s, and is primarily called by `isSymOcc` to do tests on `OccName`s. We variously need this to do things like check if a symbol name is valid (language check for `TypeOperators`) or make a decision about how to pretty-print a symbol, etc. * `okSymChar` operates on `String`s, and is used by the Template Haskell conversion interface to test that a TH-generated identifier looks like a valid symbol (if it is one.) * `notFollowedBySymbol` operates on the Alex state, and is used to make decisions in the Lexer. This one might be a bit more permissive than the others, since lexer errors are not nice for users but errors in the type- checker are much nicer. So probably `isLexVarSym` and `okSymChar` can and should be combined, but you'll have to do a goofy conversion from String to FastString to do it. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10583#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler