Steven, With
(<3;]) 4 |domain error | (<3;])4 aren't you curious to know what leads to a domain error? In infix languages like J, expressions within parens are evaluated before their results are applied. Obvious, will you say? The expression <3;] has no right arg, is thus tacit and needs evaluation to determine the valence and rank of its verbs and of its result. In <3;] ,we have a train of verb-noun-verb-verb. The trident 3;] , noun-verb-verb, is evaluated first resulting in a verb. Within the parens is now a verb-verb train, a hook. But the left verb of a hook is ALWAYS dyadic using a copy of the right arg on the left if needed; so your < verb is dyadic meaning Less-Than, not the intended monad. Is 4 Less-Than 3;4, is 4 Less-Than a boxed value? J is stricter than APL and won't look inside automatically as APL does (but you could have 4 < each 3;4). What is the rank of <3;] ? Type (<3;]) b. 0 to confirm your guess. Ref. F.Trains /j602/help/dictionary/dictf.htm. ~ Gilles ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
