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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Floating point syntax specification is incorrect","articleBody":"# Documentation\r\n\r\nThe floating point syntax spec is incorrect, and can be found in [/Doc/library/functions.rst](https://github.com/python/cpython/blob/main/Doc/library/functions.rst):\r\n\r\nThe syntax [rendered currently](https://docs.python.org/3/library/functions.html#float) is the following:\r\n\r\n```ebnf\r\nsign        ::=  \"+\" | \"-\"\r\ninfinity    ::=  \"Infinity\" | \"inf\"\r\nnan         ::=  \"nan\"\r\ndigitpart   ::=  `!digit` ([\"_\"] `!digit`)* \r\nnumber      ::=  [digitpart] \".\" digitpart | digitpart [\".\"]\r\nexponent    ::=  (\"e\" | \"E\") [\"+\" | \"-\"] digitpart\r\nfloatnumber ::=  number [exponent]\r\nfloatvalue  ::=  [sign] (floatnumber | infinity | nan)\r\n```\r\n`digitpart` should not include an exclamation point or backtick quotes. The backticks appear to be the underlying syntax failing to render, but the exclamation points have a meaning, which is an issue. This is the underlying syntax:\r\n\r\n```yaml\r\nsign: \"+\" | \"-\"\r\ninfinity: \"Infinity\" | \"inf\"\r\nnan: \"nan\"\r\ndigitpart: `!digit` ([\"_\"] `!digit`)*\r\nnumber: [`digitpart`] \".\" `digitpart` | `digitpart` [\".\"]\r\nexponent: (\"e\" | \"E\") [\"+\" | \"-\"] `digitpart`\r\nfloatnumber: number [`exponent`]\r\n```\r\n\r\nEBNF includes a \"[Special Sequences](https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form#Table_of_symbols)\" syntax, that would be appropriate for this situation, but I'm uncertain if it is possible to use in the underlying YAML format. It should be rendered like this:\r\n\r\n```ebnf\r\nsign        ::=  \"+\" | \"-\"\r\ninfinity    ::=  \"Infinity\" | \"inf\"\r\nnan         ::=  \"nan\"\r\ndigit       ::=  ? Any character in the unicode digit class ?\r\ndigitpart   ::=  digit ([\"_\"] digit)* \r\nnumber      ::=  [digitpart] \".\" digitpart | digitpart [\".\"]\r\nexponent    ::=  (\"e\" | \"E\") [\"+\" | \"-\"] digitpart\r\nfloatnumber ::=  number [exponent]\r\nfloatvalue  ::=  [sign] (floatnumber | infinity | nan)\r\n```\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-114080\n* gh-114094\n* gh-114095\n* gh-114169\n* gh-114192\n* gh-114193\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/knotapun","@type":"Person","name":"knotapun"},"datePublished":"2024-01-15T03:53:19.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/114070/cpython/issues/114070"}