Cond

1. intro.md

Create a cond function that takes 2 arguments:

1. An matrix in the format:

[
  [firstCondition, firstCallback],
  [secondCondition, secondCallback],
  ...
]

2. Any value.

So that the functions works as:

1. If firstCondition(value) is true, return firstCallback(value).
2. If secondCondition(value) is true, return secondCallback(value).
3. ...
4. If nthCondition(value) is true, return nthCallback(value).
5. Throw if no condition is true.

Example:

const x = 10

cond([
  [greaterThan10, half],
  [equals10, double],
  [lowerThan10, triple]
], x)

// returns double(10)

2. cond.js

const double = x => x * 2
const half = x => x / 2
const id = x => x
const T = () => true
const gt = n => x => x > n
const lt = n => x => x < n

const cond = (conds, x) => {
  const [, f] = conds.find(([pred, f]) => pred(x))
  return f(x)
}
  
console.log(
  cond(
  [ [gt(10), half]
  , [lt(10), double]
  , [T, id]
  ], 10)
)