cond.js

const fn = cond([
  [equals(0),   always('water freezes at 0°C')],
  [equals(100), always('water boils at 100°C')],
  [T,           (temp) => `nothing special happens at ${temp}°C`]
])
fn(0) //=> 'water freezes at 0°C'
fn(50) //=> 'nothing special happens at 50°C'
fn(100) //=> 'water boils at 100°C'