mechanicsOfMitigation.scala

import anticipation.Text
import gossamer.t
import quantitative.{Kilograms, Metres, Quantity}
import turbulence.Out

type Bmi = Quantity[Kilograms[1] & Metres[-2]]

case class Person(
  name: Text, 
  age: Int, 
  height: Quantity[Metres[1]], 
  weight: Quantity[Kilograms[1]]):
  
  def bmi: Bmi = weight / (height * height)

@main
def run(path: Text): Unit = Out.println:
  mend:
    case ParseError(line, _, _) => t"There was a parsing error at $line."
    case PathError(_, reason)   => t"There was a path error because $reason."
    case IoError(_)             => t"There was an I/O error."
  .within:
    val json = Json.parse(path.decode[Path].as[File])
    val data = unsafely(json.as[List[Person]])
    val mean = data.map(_.bmi) / data.length
    t"The average BMI is $mean"