I'm just starting to try to pick up the J language, and am confused by the following:
1 2 +/@{ i.4
1 2
+/ 1 2 { i.4
3
when in the documentation for @ it says: "x u@v y ↔ u x v y"
I assume I'm just mistaking one part of speech for another, but can't figure it out
also, how do I tell what type of speech a name is?
NB. u b. 0 returns the rank of u
NB. the rank of a verb determines the arguments it applies to at a time
NB. monadic + y applies to atoms; dyadic x + y applies to pairs of atoms
+ b. 0
0 0 0
NB. monadic +/ y and dyadic x +/ y apply to anything (unbounded rank)
+/ b. 0
_ _ _
NB. monadic { y applies to arrays of atoms;
NB. dyadic x { y applies to pairs of atoms and anything
{ b. 0
1 0 _
NB. u @ v has the rank of v
+/@{ b. 0
1 0 _
NB. since 1 2 { i.4 returns atoms at a time, +/ works on atoms
+/"0 [ 1 2 { i.4
1 2
NB. u @: v has unbounded rank
+/@:{ b. 0
_ _ _
NB. +/ applies to all of 1 2 { i.4 at once
+/"_ [ 1 2 { i.4
3
NB. mechanical translation to tacit form
13 : '+/ x { y'
[: +/ {