Hi, Attila Lendvai <att...@lendvai.name> skribis:
>> Out of curiosity, in what case do you need to represent “unset fields”? > > > i think an example works better here: consider Swarm, a p2p storage > solution. its node implementation is called Bee. bees can join > swarms. there are some well-known swarms: 'testnet' and 'mainnet'. > > when someone specifies the swarm field as a symbol naming one of the > well-known swarms, then some other mandatory fields should default to > the appropriate values derived from it, *and* the service should warn > if those fields are also set by the user. > > and when one is joining a custom swarm, as per giving a string name in > the swarm field, then the service should warn when these mandatory > fields are not explicitly specified. I see. The ‘define-configuration’ macro uses 'disabled as a way to indicate fields that have not been user-specified. Would that be of any help in this context? Another approach would be to use ‘define-record-type*’ and record all the default values, including those derived from other fields (just like the default ‘home-directory’ field of <user-account> is derived from ‘name’.) Does that make sense? Ludo’.
