Section 3.6 (Symbolic Keywords) Does the F # 2.0 Language Specification list a symbolic keyword? (the double-digit question mark) that is used today (that is, not as reserved for future use). What is his purpose? It is not mentioned in the Symbol and Operator Reference (F #) on msdn, it is not an OCAML symbol, and I have never seen an example where it is used.
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One conceivable answer: this is a symbolic keyword reserved for future use, which is accidentally placed in the list of symbolic keywords instead of future symbolic keywords. This would be strange for two reasons:
- The list of future symbolic keywords contains only two entries: ~ and `, and it is placed immediately below another list. Future symbolic keywords are something very important, it is unlikely that the author of the performance simply forgot about it.
- Section 3.7 (Character Operators) states that no symbolic operator defined by a library or user should start with a question mark, except for late-linking operators? and? thetas; Therefore, it makes no sense to even mention the future symbolic keyword with the name ", since its introduction cannot be a change.
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