Better "dot" notation sugar for mutating properties

[tjb1982]

Currently in an environment document, you can mutate maps such as

foo:
  bar:
    baz: lala
  quux:
  - first
  - second
  - third: true

like this:

foo.bar.baz: something which is not "lala"
foo.quux.2.third: false

Which is great, but in order to append to collections, it gets awkward:

foo.bar:
  ~(assoc:
  - [email protected]
  - ~:extra
  - blah

foo.quux:
  ~(conj:
  - [email protected]
  - fourth

It would be nice if there were a shortcut, like this:

foo.bar.:
  extra: blah
foo.quux.: fourth

or even:

foo.:
  bar.:
    extra: blah
  quux.: fourth