Create linear data flow with container style types

First rewrites an imperative style text manipulation with composable functions. Instead of a new line for each step, one functions embeds the next. So five lines becomes one line, but it's not really better.

##The Box

If we put the String in a Box which for now is an Array ([str]) we can chain off the actions from this array:

const nextCharForNumberString = str =>
 [str]
 .map(s => s.trim())
 .map(..)
 .map(//another step...)

The great thing about this, is that each expression (.map(s => s.trim())) is contained in its own environment.

map is composition

It takes an input, runs a function inside it, then passes the result to the next map.

###Defining our own Box

It will do the same thing as the Array.map.