Variations on a theme by comma
In APL the comma is buttressed by appendages, an integer or real number encased in brackets, to convey the ideas of adjoinging along a certain axis, or laminating a new axis after an old one. In default, mere dyad comma signifies adjoining along a trailing axis. In J these ideas are separated. Dyad comma still signifies adjoining along a terminal axis, but this is now the leading, and not the trailing axis, and in fact the definition of dyad comma is to append items. J’s two new primitive dyads append (x ,. y) and laminate (x ,: y) help to clarify this situation. a=.4 4$'readbonywakeruth' b=.'beat' c=.'cal' a,b read bony wake ruth beat b,.a bread ebony awake truth b,:c beat cal The forms ,/ and ,./ provide useful results. z abcde fghij klmno pqrst uvwxy z0123 ,/z abcde fghij klmno pqrst uvwxy z0123 ,./z abcde klmno uvwxy fghij pqrst z0123 $z NB. note leading blank in each row 3 2 6 |