f1:{(x#y;x_y)1 0=x<0}
f1[9]"SplittingHairs"
f1[-1]"ngn/k"
f1[-3]"DyalogAPL"
f1[10]@!10
f1[1]("works";"with";"words";"also")

f2:{(&^(!64)?x-128)_x}
f2 68 194 165 226 141 186 226 140 138 240 159 148 178 57
f2 68 121 97 108 111 103
f2@!0

f3:26/1+-"A"-
f3"A"
f3"APL"

f4:2!+/~400 100 4!\:
(0 0 0 1 0 0 0 1 0 0
 0 1 0 0 0 1 0 0 0 1
 0 0 0 1 0 0 0 1 0 0
 0 1 0 0 0 1 0 0 0 1
 0 0 0 1 0 0 0 1 0 0
 0 1 0 0 0 1 0 0 0 1
 0 0 0 1 0 0 0 1 0 0
 0 1 0 0 0 1 0 0 0 1
 0 0 0 1 0 0 0 1 0 0
 0 1 0 0 0 1 0 0 0 1)~f4''1901+10 10#!100
~f4@1900
f4@2000

f5:{(y-)+[-/<y,x;]\x}
f5[3]10
f5[4;-3]
f5[42]42

f6:{y@>x=y}
f6[3]2 3 4 1 3 1 4 5
3 3 2 4 1 1 4 5~f6[3]2 3 4 1 3 1 4 5

f7:&/~>/+2\,
f7[2]7
f7[4]11
f7[3]11
f7[4]0

f8:&/1_(~=/0<,)':1_-':10\
f8 123
f8 132
f8 31115
f8 3141514131415
f8'132 231 213 312 1324 1423 2314 2413 3412
f8'123 321 1234 1432 2134 2341

f9:3>+/~=':0<(0=)_-':
f9 1 3 3 4 5 2 1
f9@,42
f9 23 23 23
f9 ()
f9 1 2 1 1
f9'(1 3 1 4; 2 1 3; 3 2 1 4)