module Web

import Prelude

ptype Async : U -> U
pfunc resolve : ∀ a. a -> Async a := `(_, a) => Promise.resolve(a)`
pfunc andThen : ∀ a b. Async a -> (a -> Async b) -> Async b := `(A,B,a,ab) => a.then(ab)`
pfunc reject : ∀ a. String -> Async a := `(_, msg) => Promise.reject(msg)`

instance Monad Async where
  bind = andThen
  pure = resolve

-- It'd be nice to be able to declare operators and JS "projections"
pfunc fetchText : String -> Async String := `async (url) => {
  let response = await fetch(url)
  return response.text()
}`

pfunc liftAsync : ∀ a. IO a -> Async a := `(_, a) => Promise.resolve(a(undefined).h0)`

instance HasIO Async where
  liftIO = liftAsync

runAsync : ∀ a. Async a -> IO Unit
runAsync foo = pure MkUnit