@: (At) Conjunction
Forms the composition (u@:v) of two given verbs u and v .
The result is a tacit verb equivalent to
u v y NB. monad x u v y NB. dyad
But unlike Atop (@), the rank of (u@:v) is infinite, irrespective of the ranks of u and v.
Implement: f(g(x)) -- the mathematical composition of the two functions: f and g.
mean=: +/ % # cat=: ,&1"1 ]z=: i.2 3 NB. sample noun 0 1 2 3 4 5 cat z NB. appends 1 to each row of z 0 1 2 1 3 4 5 1 mean@:cat z NB. mean of the COLUMNS of cat z 1.5 2.5 3.5 1 mean@:cat b.0 NB. rank of (mean@:cat) _ _ _
But see Rank in a hurry: an insidious rank problem for how and when these different methods give different results.