On Wed, Feb 8, 2012 at 9:46 PM, Simon Holgate <simon.holg...@gmail.com> wrote: > Could anyone point me to a description of "->" and "->>", please? > > I've seen a few references to them (e.g. git://gist.github.com/1761143.git) > but nothing in "Programming Clojure". Google doesn't seem to like > searching for such strings.
These macros are collectively called the "threading macros". `->` is called "thread first" and `->>` is called "thread last". These macros lets you write deeply nested function invocations in a relatively flat manner. Something like (-> foo (bar x) (baz y) (quux z)) gets re-written as (quux (baz (bar foo x) y) z). So `->` basically threads the first expression through the subsequent forms, inserting it as the second item in the list (aka the first arg). Similarly, something like (->> foo (bar x) (baz y) (quux z)) gets re-written as (quux z (baz y (bar x foo))). More docs here - http://clojuredocs.org/clojure_core/clojure.core/-%3E & http://clojuredocs.org/clojure_core/clojure.core/-%3E%3E Regards, BG -- Baishampayan Ghose b.ghose at gmail.com -- 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
