Kona is an open source implementation of the APL-derived K. K, like APL is an array programming language but it uses ascii characters...so it is easier to type, if not read.

Launch it by entering the letter k at the command line.

This will drop you into the kona repl. To exit the interpreter enter \\ and then hit enter. Enter a single \ to see the kona help text.

kona wiki
learning K programming idiom by idiom

backlinks: languages.html repl.html