DrBoolean FP constructure

helepr.js

// from https://github.com/DrBoolean/Practically-Functional

const Box = x =>
({
  chain: f => f(x),
  map: f => Box(f(x)),
  fold: f => f(x),
  inspect: () => `Box(${x})`
})


const Right = x =>
({
  chain: f => f(x),
  ap: other => other.map(x),
  traverse: (of, f) => f(x).map(Right),
  map: f => Right(f(x)),
  fold: (f, g) => g(x),
  inspect: () => `Right(${x})`
})

const Left = x =>
({
  chain: f => Left(x),
  ap: other => Left(x),
  traverse: (of, f) => of(Left(x)),
  map: f => Left(x),
  fold: (f, g) => f(x),
  inspect: () => `Left(${x})`
})

const fromNullable = x =>
  x != null ? Right(x) : Left(null)

const tryCatch = f => {
  try {
    return Right(f())
  } catch(e) {
    return Left(e)
  }
}