I found this, https://github.com/peter-shoes/plankalkul https://github.com/peter-shoes/plankalkul, a Java implementation based on the 2000 modernization by Raul

I found this, https://github.com/peter-shoes/plankalkul https://github.com/peter-shoes/plankalkul, a Java implementation based on the 2000 modernization by Raul Rojas. And another one, https://github.com/Hovestar/Plankalkul https://github.com/Hovestar/Plankalkul, based on a bachelors thesis, http://www.cs.ru.nl/bachelors-theses/2010/Bram_Bruines___0213837___Plankalkul.pdf http://www.cs.ru.nl/bachelors-theses/2010/Bram_Bruines___021.... This one in Ruby by a GraalVM member has the best examples I think: https://github.com/timfel/plankalkul2ruby https://github.com/timfel/plankalkul2ruby.