ref: ef67435f5e2b0937c1da262d59c6a10394203743 dhall-ruby/lib/dhall d---------
Fix for #join on empty list
Do not commute generally

The operator is commutative, but that doesn't mean x == False should
become False == x upon normalization.
Update to latest dhall-lang

* Allow selection from union Kind or Sort
* End of line is always \n (for multiline test case)
* Multiline of only blank lines should not error
Switch IntegrityCheck encoding to multihash
Split IntegrityCheck and NoIntegrityCheck
Split IntegrityCheck and NoIntegrityCheck
Refactor builtins

The fill/unfill code is much simpler now
IntegrityCheck stores raw hash internally
Decode unions the same way as_dhall makes them
Use Dhall names for everything that encodes untagged
Disambiguate hoisted union tags properly

An array may contain two nomnatively-equivalent types who are
structurally different -- so they need different (but related) union
tags since they will not share a type.
Enum should not have itself in the alts
More useful to_s for AST nodes
Normalize list element types before comparing
Facility to flatten let blocks
Allow typechecking filled builtins
Add new useful facilities to Function
as_dhall for Proc

Cannot actually serialize this, but can be useful for passing functions
in to Dhall functions, etc.
Update to latest dhall-lang