The Readme defines:

  // Data NonEmpty = | New a (NonEmpty a) 
  NonEmpty 
    |A :: ~ * ~> * => {(list A) :: |new}. // A list non-empty is list only with new constructor

The haskell datatype reads like a co-inductive definition: a stream of list elements. But the NonEmpty in your language should be

  data NonEmpty = New a (List a)

right?