Eachpair

Eachpair Adverb

The eachpair adverb ': applies its verb to each adjacent pair of elements in the argument.

  -': 1 3 7 15 /minus each pair, or "deltas"
2 4 8
  -': 100 10 1
-90 -9
  %': 1 10 1000 1e6 /divide each pair, or "ratios"
10 100 1000.0
  2.0 %': 1 10 1000 1e6 /left argument prepends
2 10 100 1000.0

This works much as you would expect, though note that eachpair reverses the order of the arguments it passes to the verb or function.

  {x-y}': 1 3 7 15
2 4 8
  {y-x}': 1 3 7 15
-2 -4 -8