Compiler: better support for promise chains

[josephjclark]

Did we miss a trick with promise chains? Should we be able to support an operation inside a .then callback?

We can currently do this:

each(
  $.items,
  post(`patient/${$.data.id}`, $.data).then(state => {
    state.completed.push(state.data);
    return state;
  })
);

But surely it would be cool to support this?

each(
  $.items,
 get(`patient/${$.data.id}`)
   .then(post(`patient/${$.data.id}`, $.data))
   .then((state => {
    console.log('done!')
    return state
  })
)

What I'm saying is that inside then() we should be able to write an operation, without a ()(state) wrapper.

Either compiler code, or some magic in promises (perhaps even a custom promise library), would have to "unwrap" the operation.

Something like this maybe?

each(
  $.items,
 get(`patient/${$.data.id}`)
   .then((state) => post(`patient/state{state.data.id}`, state.data)(state))
   .then((state => {
    console.log('done!')
    return state
  })
)

But my feeling is:

• .then() is called with state
• .then(get()) will pass a function into .then(), which will be lazily executed
• Can we extend .then() to recognise that an Operation has been passed in, and handle it appropriately? I should have all the information it needs.