Then I realised that I could run parsers in an interleaved way, and wrote the package uu-interleaved”. In remarkably few lines of code this can turn a parser combinator library in a a library that can run parsers in an interleavedway . If you look at the code in:

this boils down to writing a few instances for a new data type. Although the code is intricate it is very short, and the types guided me get the code correct. Without te types I would have spent ages in getting things to work.

The I realised that by adding just a few extra lines of code this could be turned in a package for writing code for dealing with command line arguments in a very broad sense: repeating arguments, dealing with missing obligatory arguments, optional arguments and parsing the arguments according to what they stand for and reporting errors in the command line in a systematic way 

Surprisingly the  the code of this package is probably less that what an ordinary program spends on processing it's command line arguments, while providing much larger security.

 [End of shameless promotion]

If your audience consists of experienced programmers they must have been spending quite some time on code that is no longer necessary when using such a package.

 Doaitse