Add a compose export

[RichardForrester]

I've noticed that implementations of compose vary greatly and especially the libraries that support placeholders seem to fail on Builders.

I thought it would be better if njsx supplied it's own compose function so I added.

Let me know if you can try it out and if you have any issue with it.

[RichardForrester]

Don't pull yet. I've noticed some artifacts from this compose function. I have a different one that works better with Builders and has better typescript support. I will commit as soon as I check everything out.

What do you think about the API?

It's not a true compose as in Haskell which only takes two arguments. It's really a pipeLeft which I abbreviate as pL in my projects. But for njsx, I was thinking composeBuilders, but that's too long.

[RichardForrester]

Hey, I'm going to get back to this later tonight and add support for more arguments, I think 12 should be enough and change the implementation so that it does not need to be called, explained below.

I realized that you don't really want to supply the final argument to the compose function as you would normally. Basically want to list your nested Builders and just return a Builder. It can be done with this commit by calling the composition with (null):

import { composeBuilders } from 'njsx'

const Root = ({ store }) =>
  composeBuilders(
    Provider({ store }),
    PersistGate({ loading: null, persistor }),
    Router({ history }),
    Route({ path: '/', component: App })
  )(null)()

However, I think it would be better to not even have to call it with null. I've got to run and do family stuff now, but if you get a chance let me know what you think and I'll finish it up tonight.

I'm thinking nest would be a good name. So the final API might be something like:

import { nest } from 'njsx'

const Root = ({ store }) =>
  nest(
    Provider({ store }),
    PersistGate({ loading: null, persistor }),
    Router({ history }),
    Route({ path: '/', component: App })
  )()