identity-functor.amb

string_length[
  in_ call.open call.(
    func[
      str[in_ arg.open arg.in int.in length.open_]|
      int[
        length[in_ str.open str]|
        in_ str
      ]|
      open_
    ]|
    open return.open_
  )
]|
map_identity[
  in_ call.open call.(
    func[
      id[in_ arg.open arg.open identity.in arg.open_]|
      arg[in_ id.open id.in func.in arg.open_]|
      func[in_ func.in_ arg.open func.in identity.open func.open_]|
      identity[
        in_ func.open func
      ]|
      open_
    ]|
    open return.open_
  )
]|
program[
  out_ call.in_ map_identity|
  out_ call.in_ string_length|
  open func.open_|
  
  call[
    out program.in map_identity.open_.return[open_.in program.in func]
  ]|
  call[
    out program.in string_length.open_.return[open_.in program.in func.in func]
  ]|
  func[in_ map_identity.open map_identity.(
    arg[
      identity[
        string[hello[]]|open_
      ]|
      in id.open_
    ]|
    func[
      arg[in_ arg.open arg.in str.open_]|
      in_ string_length.open string_length.in func.open_
    ]|
    in_ string_length.open func.open_)
  ]
]|
open program