Hi Everyone, The set of classes for which seq? returns true is rather large. It contains Cons, LazySeq, PersistentList, and many others. Experimentation reveals that any of these types can be used to hold Clojure code for evaluation by eval.
Is a form just anything for which seq? returns true, by definition? Or is there a more accurate definition of a form? If it's correct to say that a form is always something for which seq? returns true and never something for which seq? returns false, then any ISeq-implementing type can be used to hold the return values of quote and syntax-quote, in principle. Currently, user=> (class '(f arg1 arg2)) clojure.lang.PersistentList user=> (class `(f arg1 arg2)) clojure.lang.Cons But those particular classes might be just implementation details. In principle, in a future release, one or both of those calls might return ChunkedCons or LazySeq, or any of the other ISeq-implementing types. I am wondering whether someone could guarantee that this potentiality will *not* come to pass. To put the question differently, is there a subset of the ISeq-implementing classes that is guaranteed never to be used to hold the output of quote, syntax-quote, or any other core code-generation facilities? In particular, can it be guaranteed that quote and syntax-quote will never return a lazy-seq? (I can't see why it would ever be desired that they should, but I am wondering whether a guarantee is available.) Perhaps no such guarantee is available because it is an implementation detail that quote and syntax-quote return Java objects in the first place. In another release they might return deftypes or CLR objects. In that case, is there any internal-to-Clojure facility I can use to differentiate between seqs generally, on one hand, and the return values of quote and syntax-quote, on the other hand? Is there any way I can generate a "clojure-generated-form?" predicate that is more restrictive than "seq?"? Thanks, Garth -- 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
