import strutils

type FloatRange = tuple[s,e: float]

proc mapRange(a,b: FloatRange, s): float =
  b.s + (s - a.s) * (b.e - b.s) / (a.e - a.s)

for i in 0..10:
  let m = mapRange((0.0,10.0), (-1.0, 0.0), float(i))
  echo i, " maps to ", formatFloat(m, precision = 0)