Here is a comment from Chapter 40 of J for C Programmers: The verb [:, which we met as a way to cause an error, has a special meaning in a fork. As the leftmost verb of the fork, [: means 'ignore the left branch'. So, Nx ([: V1 V2) Ny is V1 Nx V2 Ny and ([: V1 V2) Ny is V1 V2 Ny . In both cases, ([: V1 V2) is equivalent toV1@:V2 . Almost always, the choice between one form or the other is a matter of taste. Do not fear that the extra word in the fork leads to slower execution; the [: is not executed--it is recognized by the parser when it creates the anonymous verb for the fork.
Kip Murray Sent from my iPad On Nov 29, 2012, at 11:38 AM, Ian Clark <earthspo...@gmail.com> wrote: > Thanks Dan. > > What I'm hearing reassures me. > > I'm in the final testing phase of an explication utility. It assumes > the production: ([: f g) ==> f@:(g) . I just had a panic attack > and wondered if (and whereabouts) this was guaranteed. > > IanClark > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
