Cont monad in javascript with flowtype

+flow-cont-monad.js

// @flow

type Cont<R, A> = (A => R) => R;

const ret = <R, A>(a: A): Cont<R, A> =>
  k => k(a);

const bind = <R, A, B>(cont: Cont<R, A>, fn: A => Cont<R, B>): Cont<R, B> =>
  k => cont(a => fn(a)(k));

const add = <R>(a: number, b: number): Cont<R, number> => ret(a + b);
const sqr = <R>(a: number): Cont<R, number> => ret(a * a);

const pythag = <R>(a: number, b: number): Cont<R, number> =>
  bind(sqr(a), aSqrd =>
  bind(sqr(b), bSqrd =>
  add(aSqrd, bSqrd)));

const callCC = <R, A, B>(fn: (A => Cont<R, B>) => Cont<R, A>): Cont<R, A> =>
  k => fn(a => _ => k(a))(k);

pythag(2, 3)(console.log);

// `() => ret(25)` should never be called
const quux = callCC(cc =>
  bind(cc(5), () =>
  ret(25)))

quux(console.log);

.flowconfig

[ignore]

[include]

[libs]

[lints]

[options]

[strict]

package-lock.json

{
  "name": "flow-cont-monad",
  "version": "1.0.0",
  "lockfileVersion": 1,
  "requires": true,
  "dependencies": {
    "babylon": {
      "version": "6.18.0",
      "resolved": "https://registry.npmjs.org/babylon/-/babylon-6.18.0.tgz",
      "integrity": "sha512-q/UEjfGJ2Cm3oKV71DJz9d25TPnq5rhBVL2Q4fA5wcC3jcrdn7+SssEybFIxwAvvP+YCsCYNKughoF33GxgycQ==",
      "dev": true
    },
    "flow-bin": {
      "version": "0.62.0",
      "resolved": "https://registry.npmjs.org/flow-bin/-/flow-bin-0.62.0.tgz",
      "integrity": "sha1-FLymaabj+VwLwMLR61XsTpjLHYM=",
      "dev": true
    },
    "flow-remove-types": {
      "version": "1.2.3",
      "resolved": "https://registry.npmjs.org/flow-remove-types/-/flow-remove-types-1.2.3.tgz",
      "integrity": "sha512-ypq/U3V+t9atYiOuSJd40tekCra03EHKoRsiK/wXGrsZimuum0kdwVY7Yv0HTaoXgHW1WiayomYd+Q3kkvPl9Q==",
      "dev": true,
      "requires": {
        "babylon": "6.18.0",
        "vlq": "0.2.3"
      }
    },
    "vlq": {
      "version": "0.2.3",
      "resolved": "https://registry.npmjs.org/vlq/-/vlq-0.2.3.tgz",
      "integrity": "sha512-DRibZL6DsNhIgYQ+wNdWDL2SL3bKPlVrRiBqV5yuMm++op8W4kGFtaQfCs4KEJn0wBZcHVHJ3eoywX8983k1ow==",
      "dev": true
    }
  }
}

package.json

{
  "name": "flow-cont-monad",
  "version": "1.0.0",
  "description": "",
  "main": "+flow-cont-monad.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "flow-bin": "^0.62.0",
    "flow-remove-types": "^1.2.3"
  }
}