E:{:[@y;y x;(,y),x]}

d:{x[,0],x}              / duplicate the top of the stack
c:{(x[,0],x 1),2_ x}     / cons the top two elements of the stack
i:{(1_ x)E/*x}           / evaluate the top of the stack on the rest

q:(`d`c;`d;`c)

()E/q

()E\q