Dhall schema extensions

DhallSchema.md

Useful Dhall operations/tools:

Common subexpr elimination:

[ < L | R | X >.L, < L | R | X >.R ] 
  =cse=> 
let _ = < L | R | X > in [ _.L, _.R ]

For any expr e

 cse(e) =normalize=> e

Simplify unions (recursively over records and lists):

[ < L | R | X >.L, < L | R | X >.R ] 
  =simpl=>
[ < L | R >.L, < L | R >.R ] 

Generalize (a la TIDL):

  (< A >.A as < A | B >) => < A | B >.A
  { foo = 1 } as { foo : Int, bar : Optional Bool } => { foo = 1, bar = None Bool }

etc.

For any type T and (x : T), where T is constructed out of records, unions, lists, optional and primitives:

   simpl(x) as T : T
   simpl(x) as T = x