Add BQN Lang

[suhr]

BQN is an array programming language, similar to APL and J.

[razetime]

The current fast implementation of BQN resides at https://github.com/dzaima/CBQN/.
One problem is that getting input from STDIN is supported by a temporary function •GetLine and will probably be replaced by a different system. Output is possible with •Show and •Out, and there is no implicit output by default.

However, file input/output and •args are already documented in the BQN spec. If it's possible to include BQN with these limitations, it should be doable. Otherwise it's best to hold this until further updates to the language.