220 def pps(es: Rexp*) = indent(es.map(pp))

   220 def pps(es: Rexp*) = indent(es.map(pp))

   221 

   221 

   222 

   222 

   223 @main

   223 @main

   224 def test4() = {

   224 def test4() = {

   225   println(pp(r2))

   226   println(pp(r2))

   226   println(pp(ders("x".toList, r2)))

   227   println(pp(ders("x".toList, r2)))

   227   println(pp(ders("xy".toList, r2)))

   228   println(pp(ders("xy".toList, r2)))

   228   println(pp(ders("xyz".toList, r2)))

   229   println(pp(ders("xyz".toList, r2)))

   229 }

   230 }