λ(nix : ../NixPrelude.dhall) →
  let Any = ../Any/Type.dhall

  let Set = ../Set/Type.dhall

  let Any/toAny = ../Any/toAny.dhall nix

  let Any/toTypeUnchecked = ../Any/toTypeUnchecked.dhall nix

  let fixp = (./fix.dhall nix).fixp

  let Set/toSet = ../Set/toSet.dhall nix

  let Set/mergeAttrs = ../Set/mergeAttrs.dhall nix

  let extends = ./extends.dhall nix

  let FunctionType = λ(x : Type) → x → Text → (Set → Set) → Set

  let function =
        λ(function : FunctionType Any) →
          let functionArgs =
                Any/toTypeUnchecked
                  (FunctionType (FunctionType Any))
                  (Any/toAny (FunctionType Any) function)
                  function

          in  λ(extenderName : Text) →
              λ(rattrs : Set → Set) →
                let extset =
                      Set/toSet
                        ((Set → Set → Set) → Set)
                        [ { mapKey = extenderName
                          , mapValue =
                              λ(f : Set → Set → Set) →
                                functionArgs extenderName (extends f rattrs)
                          }
                        ]

                in  Set/mergeAttrs (fixp rattrs) extset

  let functionErased =
        Any/toTypeUnchecked
          (FunctionType Any)
          (Any/toAny (FunctionType (FunctionType Any)) function)

  let makeExtensibleWithCustomName
      : Text → (Set → Set) → Set
      = function functionErased

  in  makeExtensibleWithCustomName