{.  (Verb)

HEAD (_)  {.y selects the leading item of y; that is, y if y is an atom, and 0{y if not.

TAKE (1 _)  If x is an atom, x{.y takes from y an interval of |x items; beginning at the front if x>:0, ending at the tail if x<0:

	 y	    2{.y	    4{.y   	 _4{.y
0 1   0 1		    0 1	     0 0
2 3   2 3		    2 3	     0 1
4 5			         4 5	     2 3
				           0 0 	    4 5

In an overtake (as in 4{.y and _4{y above), extra items consist of fills; zeros if y is numeric, boxed empties if it is boxed, and spaces otherwise. If y is an atom, the result of 1{.y is a one-element list. Finally, if $y is 0,s, then the fill items are s$0 or s$<'' or s$' '.

In general, x may be a list of length not more than $$y; the effect of element k is       (k{x){."(($$y)–k) y.