On May 26, 2013 8:53 PM, "Mark Engelberg" <mark.engelb...@gmail.com> wrote: > > Another possible design choice is to store a domain-testing predicate in the function's metadata.
Using metadata would be a much more idiomatic choice than using arity. Multiple arities are idiomatically used (like method overloading) to default arguments. An interesting detail James thought of but didn't call out is putting the domain check in the :pre metadata of the fn. This is an infrequently used Clojure feature, but it's a perfect fit for partial functions. Calling a fn with an argument that fails the :pre check will throw an exception, so the body can be written to assume it's got good input. Anyone can grab the :pre metadata to test for applicability, and anyone who knows clojure will have at least passing familiarity with the concept. Your macro can still pull apart the pattern matching forms to build the :pre fn, and it's still easy to do orElse-style composition. Unrelated: If you haven't already, you may want to read and follow up on the May 16 thread "core.match" before going very far with it. -- -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
