> The part after the argument vector goes into the function body, which > is wrapped in a do. do evaluates the expressions and returns the > value of the last one. The results of evaluating the other expressions > are discarded.
Ok. That provides the clarity I was after. Thank You. It looks like I was getting turned around by the implicit do (and by my preconceptions coming from other Lisps where the docstring likes to sit behind the arglist) Maybe a common enough mistake for those making the transition... > Many languages work this way. In Ruby: Some don't :) > def foo > "evaluted and lost" > "return value" > end So, it would have been safer to assume Ruby like behaviour :) On Dec 4, 2:22 am, Meikel Brandmeyer <[EMAIL PROTECTED]> wrote: > Hi, > > On 4 Dez., 07:53, Mon Key <[EMAIL PROTECTED]> wrote: > > > So, in the case where the (doc)string is placed after the param I > > should expect that REPL reads that string but doesn't necesarily > > evaluate it? Where does that string go? Does it become nil? It > > wasn't passed as a nil anymore than it was passed as a docstring. > > I'm not sure I understand correctly what you are asking for > but the following is my understanding what happens. > > (defn foo > "docstring here" > [x y] > (+ x y)) > > This - as discussed before - places the string in the metadata > of the Var foo, not the function itself. Functions cannot be > associated with metadata. > > (defn foo > [x y] > "some string here" > (+ x y)) > > This is a function which first evaluates "some string here", > which happens to evaluate to itself since it is a string. However > since the string is not the last expression of the function body > it is discarded and evaluation goes on with the next expression. > > Since there is no docstring it is not assigned to the metadata > of the Var foo, which refers to the function. Hence retrieving > it will return nil. > > > Following defns do not evaluate as equivalent - nor are they identical > > - nor do they appear to share the same identity. > > I can understand cases for passing the empty string, the empty list, > > etc. However, I have trouble understanding how it isn't an error/ > > exception to pass a non-empty string after the param list and have > > that string be converted to nil. > > Ok. Let's try to understand what happens. Say you the second foo > function of above. Then a call (foo 1 2) is roughly equivalent to the > following: > > (let [x 1 > y 2] > (do > "some string here" > (+ x y))) > > The part after the argument vector goes into the function body, which > is wrapped in a do. do evaluates the expressions and returns the > value of the last one. The results of evaluating the other expressions > are discarded. > > So in (defn foo "string" [] ...) "string" is a docstring, while in > (defn foo [] "string" ...) "string" is part of the function body. > > Hope this helps. > > Sincerely > Meikel --~--~---------~--~----~------------~-------~--~----~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
