On Thu, Jun 23, 2011 at 11:55 AM, B Smith-Mannschott <bsmith.o...@gmail.com> wrote: > user> (name 'a/b/c) > "c" > user> (namespace 'a/b/c) > "a/b" > > Is this intentional? I would have expected a/b/c to be > rejected as a symbol name since we use slashes to separate > namespace from name and conventionally use "." to indicate > hierarchy in namespace names.
=> (namespace (symbol "" "a/b")) "" => (name (symbol "" "a/b")) "a/b" Both the namespace and the name can contain slashes, but the normal reader behavior is that foo/bar/baz is interpreted as namespace up to the last slash and then name. Unless the symbol is just "/", in which case the reader treats that as the name, with no namespace. (Necessary for a bare / to resolve, ordinarily, to the division function clojure.core//). You can get any desired symbol using the two-argument form of the symbol function, though. There's some ickiness here. For instance the one-argument form of symbol doesn't parse the same as the reader does: => (clojure.core// 42 2) 21 => (eval (list (symbol "clojure.core//") 42 2)) #<CompilerException java.lang.StringIndexOutOfBoundsException: String index out of range: 0 (NO_SOURCE_FILE:1)> => (eval (list (symbol "clojure.core" "/") 42 2)) 21 In fact, (symbol "clojure.core//") produces a symbol with namespace "clojure.core/" and name "", the latter of which apparently leads to the rather obfuscatory error message above. Symbols whose names contain slashes don't work as vars -- another cryptic message, since the symbol's actually unqualified here: => (eval (list 'def (symbol "" "foo/bar") 42)) #<CompilerException java.lang.Exception: Can't refer to qualified var that doesn't exist (NO_SOURCE_FILE:1)> And symbols whose namespaces contain slashes won't work as vars with AOT, if at all, since the namespace name ends up a class file name and slashes are path separator characters on every sane filesystem and thus cannot appear in file names. Moral of the story: try to avoid slashes in symbol names, except for the unqualified name of the division operator. :) But if you really for some reason need one it can be done, though the only apparent use for such a symbol is as a kind of auto-interning string rather than as a var name. You'd probably be better off using a keyword for such uses. -- Protege: What is this seething mass of parentheses?! Master: Your father's Lisp REPL. This is the language of a true hacker. Not as clumsy or random as C++; a language for a more civilized age. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
