The test cases have been tested using Marcel
van der Veer's "Algol 68 Genie (Algol68G)" implementation, see
"http://www.xs4all.nl/~jmvdveer/algol.html". This is a pretty
full Algol implementation, lacking only parallel clauses of the
important constructions, but adding the Gnu Plotlib, some Gnu
"numerical procedures" and some Unix stuff [not used in these
programs] as part of the standard environment.