RiscLua is a small easily learnt programming language
for RISC OS. You can find a tutorial introduction to it
here in RiscLua for Beginners
and an example worked out in detail here in RiscLua tips
. You can also find a discussion of similarities
between BBC Basic and RiscLua.
For an introduction to the lpeg library, which provides
very powerful facilities for matching patterns and catching data
within text, see Around PEGs
or Parser expression Grammars
The RiscLua package consists of an application !lua,
that contains its own documentation.