mmstor-compilation.mm

When the traverser starts at a type (`obj{0}`), the traverser yields a type checked and compiled type. 
The technique is called *abstract interpretation*.

```groovy
mmlang> obj{0}[=mmkv,'data/mmkv.mm'][get,'v'][is,[get,'age',int][gt,28]][get,'name'][plus,'!']
==>str{*}<=[=mmkv,'data/mmkv.mm'][get,'v'][is,bool{*}<=rec['name'->str,'age'->int]{*}[get,'age'][gt,28]][get,'name'][plus,'!']
```

When you append an `[explain]` instruction, the traverser walks his current type reference and creates a `str`
table representation of the domain/range of all the types used in the composition.

```groovy
mmlang> obj{0}[=mmkv,'data/mmkv.mm'][get,'v'][is,[get,'age',int][gt,28]][get,'name'][plus,'!'][explain]
==>str<=[start,'
str{*}<=[=mmkv,'data/mmkv.mm'][get,'v'][is,bool{*}<=rec['name'->str,'age'->int]{*}[get,'age'][gt,28]][get,'name'][plus,'!']

instruction                                                       domain                                 range                            state
------------------------------------------------------------------------------------------------------------------------------------------------
[=mmkv,'data/mmkv.mm']                                            obj{0}                            =>   mmkv{*}
[get,'v']                                                         mmkv{*}                           =>   rec['name'->str,'age'->int]{*}
[is,bool{*}<=rec['name'->str,'age'->int]{*}[get,'age'][gt,28]]    rec['name'->str,'age'->int]{*}    =>   rec['name'->str,'age'->int]{*}
 [get,'age']                                                       rec['name'->str,'age'->int]{*}   =>    int{*}
 [gt,28]                                                           int{*}                           =>    bool{*}
[get,'name']                                                      rec['name'->str,'age'->int]{*}    =>   str{*}
[plus,'!']                                                        str{*}                            =>   str{*}
']
mmlang>
```