#14473: Implement Underscores in Numeric Literals Proposal (NumericUnderscores extension) -------------------------------------+------------------------------------- Reporter: takenobu | Owner: takenobu Type: task | Status: patch Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #13126 #9224 | Differential Rev(s): Phab:D4235 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"4a13c5b1f4beb53cbf1f3529acdf3ba37528e694/ghc" 4a13c5b1/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="4a13c5b1f4beb53cbf1f3529acdf3ba37528e694" Implement underscores in numeric literals (NumericUnderscores extension) Implement the proposal of underscores in numeric literals. Underscores in numeric literals are simply ignored. The specification of the feature is available here: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/000 9-numeric-underscores.rst For a discussion of the various choices: https://github.com/ghc-proposals/ghc-proposals/pull/76 Implementation detail: * Added dynamic flag * `NumericUnderscores` extension flag is added for this feature. * Alex "Regular expression macros" in Lexer.x * Add `@numspc` (numeric spacer) macro to represent multiple underscores. * Modify `@decimal`, `@decimal`, `@binary`, `@octal`, `@hexadecimal`, `@exponent`, and `@bin_exponent` macros to include `@numspc`. * Alex "Rules" in Lexer.x * To be simpler, we have only the definitions with underscores. And then we have a separate function (`tok_integral` and `tok_frac`) that validates the literals. * Validation functions in Lexer.x * `tok_integral` and `tok_frac` functions validate whether contain underscores or not. If `NumericUnderscores` extensions are not enabled, check that there are no underscores. * `tok_frac` function is created by merging `strtoken` and `init_strtoken`. * `init_strtoken` is deleted. Because it is no longer used. * Remove underscores from target literal string * `parseUnsignedInteger`, `readRational__`, and `readHexRational} use the customized `span'` function to remove underscores. * Added Testcase * testcase for NumericUnderscores enabled. NumericUnderscores0.hs and NumericUnderscores1.hs * testcase for NumericUnderscores disabled. NoNumericUnderscores0.hs and NoNumericUnderscores1.hs * testcase to invalid pattern for NumericUnderscores enabled. NumericUnderscoresFail0.hs and NumericUnderscoresFail1.hs Test Plan: `validate` including the above testcase Reviewers: goldfire, bgamari Reviewed By: bgamari Subscribers: carter, rwbarton, thomie GHC Trac Issues: #14473 Differential Revision: https://phabricator.haskell.org/D4235 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14473#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler