import { mapOutput } from 'io-ts-types/lib/mapOutput'
import { createOptionFromNullable } from 'io-ts-types/lib/fp-ts/createOptionFromNullable'

// Input: t.Type<Option<number>, number | null, t.mixed>
const Input = createOptionFromNullable(t.number)

const toUndefined = <A>(x: A | null): A | undefined => (x === null ? undefined : x)

// Output: t.Type<Option<number>, number | undefined, t.mixed>
const Output = mapOutput(Input, toUndefined)

assert.strictEqual(T.encode(none), undefined)
assert.strictEqual(T.encode(some(1)), 1)

import { Newtype, iso } from 'newtype-ts'

type Age = Newtype<'Age', number>

type Person = {
  name: string
  age: Age
}

import * as t from 'io-ts'
import { fromNewtype } from 'io-ts-types/lib/newtype-ts/fromNewtype'

const Person = t.type({
  name: t.string,
  age: fromNewtype<Age>(t.Integer)
})

import { iso } from 'newtype-ts'
import { Lens } from 'monocle-ts'

type Person = t.TypeOf<typeof Person>

const ageLens = Lens.fromProp<Person, 'age'>('age').composeIso(iso<Age>())

const sum = (a: number) => (b: number) => a + b

console.log(Person.decode({ name: 'Giulio', age: 44 }).map(ageLens.modify(sum(1))))
// => right({ name: 'Giulio', age: 44 })