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[CLJ-1003] :100 is a valid Clojure keyword. Is that intentional? Created: 27/May/12  Updated: 06/Sep/13  Resolved: 06/Sep/13

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Brian Taylor Assignee: Unassigned
Resolution: Duplicate Votes: 0
Labels: reader


In the latest clojure (eccde24c7),

These parse as keywords:


This is an error:


Is this behavior intentional?

In LispReader.java, the pattern for a symbol (and keyword) is "[:]?([\\D&&[^/]].*/)?([
D&&[^/]][^/]*)". If I'm mentally parsing that correctly, it seems like none of my examples should be valid keywords. I don't know why the first two cases parse.

http://clojure.org/reader says that none of my examples should parse.

Clojurescript does not accept any of my examples, see CLJS-142

Comment by Andy Fingerhut [ 13/Sep/12 6:34 PM ]

The reason that :100 parses as a keyword is that [
D&[^/]] matches a colon character, too. So the first : of :100 is not matching the [:]? at the beginning of the regular expression, but by a later part of it. Regexps can be tricky.

Whether this is intentional or not, my guess is probably not. Given that the docs at http://clojure.org/reader also say "A symbol can contain one or more non-repeating ':'s", writing a regexp that matches only what is documented there looks fairly complex.

Clojure has a history of allowing things, without throwing exceptions or giving any other errors, even if they are documented as not legal. This may be one of those cases. Do not consider this last paragraph as any kind of authoritative answer. It is only my observation.

Comment by Andy Fingerhut [ 05/Sep/13 5:26 PM ]

Perhaps this should be marked as duplicate of CLJ-1252

Comment by Alex Miller [ 06/Sep/13 7:50 AM ]

Dupe of CLJ-1252

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