dhall & dada s-expressions

sexpr.dhall

    let id = ./dada/id 

in  let SexprF = λ(f : Type) → < Str : Text | Int : Integer | Sexpr : List f >

in  let SexprC = λ(f : Type) → constructors (SexprF f)

in  let map =
            λ(a : Type)
          → λ(b : Type)
          → λ(fn : a → b)
          → λ(sexp : SexprF a)
          → merge
            { Str =
                (SexprC b).Str
            , Int =
                (SexprC b).Int
            , Sexpr =
                  λ(xs : List a)
                → (SexprC b).Sexpr (./prelude/List/map  a b fn xs)
            }
            sexp
            : SexprF b

in  ./dada/Mu/recursive  SexprF { map = map }