The ¨ ('each') operator applies its operand to each element of its argument. In the case of a scalar operand, or a scalar function, each has no effect.
DAYS„'MONDAY' 'TUESDAY' ½¨DAYS 6 7 DATA„(2 2½¼4) (¼10) 97.3 (3 4½'K') ½DATA (Length 4 nested vector) 4 ½¨DATA (Shape of each element, note empty vector 2 2 10 3 4 shape for element 3, the scalar) ½½¨DATA (4 shapes returned) 4 ½¨½¨DATA (The shape of each of the shapes - the 2 1 0 2 ranks - of each element)
The two-argument form of each applies is left argument and its operand to each element of its right argument. Again, for empty left or right arguments, a fill function is applied.
(1 2 3),¨4 5 6 (Joining successive pairs of elements in 1 4 2 5 3 6 the left and right arguments) 2 3†¨'MONDAY' 'TUESDAY' (2† of first element of right argument MO TUE 3† of the second) 2†¨'MONDAY' 'TUESDAY' (Scalar extension results in 2† of each MO TU element of the right argument) 2 3½¨1 2 (2½ of first element, 3½ of second) 1 1 2 2 2 4 5½¨'THE' 'CAT' THET CATCA