Module System of Egison (from version 3.4.0)

mod.egi

(module $Main
  {
   [String {string}]             ; import only string
   [$S [String {append concat}]] ; import only append and concat (with 'S.' as prefix)
   [$S String]                   ; import all exported functions (with 'S.' as prefix)
   }
  {main}                         ; export main
  )

(define $main
  undefined)