Features

- statically type checked by Flow
- PureScript-like standard library
- static land compatible

The idea (faking higher kinded types in Flow) is based on the paper Lightweight higher-kinded polymorphism and elm-brands.

Example

``js
import * as maybe from 'flow-static-land/lib/Maybe'
import * as arr from 'flow-static-land/lib/Arr'

const f = (n) => n * 2
const g = (n) => n + 1

// functor
maybe.map(f, maybe.Nothing) // => null
maybe.map(f, maybe.of(3)) // => 6

const a1 = arr.inj([f, g])
const a2 = arr.inj([1, 2, 3])

// applicative
arr.ap(a1, a2) // => [2, 4, 6, 2, 3, 4]
`

Statically type checked

`js
maybe.map(f, maybe.of('s'))
`

Error

`
maybe.map(f, maybe.of('s'))
^^^^^^^^^^^^^ call of method of
const f = (n) => n * 2
^ string. This type is incompatible with
const f = (n) => n * 2
^^^^^ number
`

Related libraries

- static-land-recursion-schemes

Related blog posts

- Higher kinded types with Flow
- Expressing side effects with the Eff monad
- Phantom types with Flow

More examples

examples directory:

- a Signal library (purescript-signal porting)
- a QuickCheck library (purescript-quickcheck partial porting)

Setup

`sh
npm install flow-static-land --save
`

Babel config

`json
{
"presets": ["es2015"],
"plugins" : [
"syntax-flow",
"transform-flow-strip-types",
"transform-class-properties"
]
}
``

License

The MIT License (MIT)