Attila Lendvai <att...@lendvai.name> skribis: >> 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?).
How about using ‘*unspecified*’ in those cases? Out of curiosity, in what case do you need to represent “unset fields”? I think in most or all of the existing configs, fields always have a default value, there’s no “unset” state. Thanks, Ludo’.
