> There’s no widespread “Maybe” idiom in Scheme; or rather, people use > TYPE | #f as a way to approximate “Maybe”. It’s not ideal, primarily > because appropriate handling is not statically checked. Yet, that’s > what we have and I’m not convinced adding SRFI-189 to the mix would > bring enough of an improvement to justify it. > > Thoughts?
configurations are full of boolean fields, where #f is a valid value. to represent unset fields, we would essentially need to implement half of srfi-189 (Maybe and Nothing), and in a potentially buggy way (e.g. using a symbol like 'disabled to represent an unset field value (i.e. the current solution) clashes with a field type of symbol?). i don't think it's worth rolling our own when an srfi covers what we need. -- • attila lendvai • PGP: 963F 5D5F 45C7 DFCD 0A39 -- “Go find yourself first, so you can find me.” — Rumi (1207–1273)