Other higher-order functions

3-argument map:

map(b, [x₁,x₂,x₃], [y₁,y₂,y₃]) ==> [b(x₁,y₁), b(x₂,y₂), b(x₃,y₃)]

map(+, [1,3,7], [2,9,5]) ==> [3,12,12]

map((x,y) Þ y/x, [1,3,7],[2,9,5])

 ==> [2/1, 9/3, 5/7]

 ==> [2,3,0]

map((x,y) Þ float(y)/x,   "   )

 ==> [2.0, 3.0, 0.7148]