fl should support regular expressions for retrieval

Solr currently supports only two syntax for retrieving fields.
fl = * (Retrieves all stored fields)
fl = fl1, fl2, fl3, (retrieves stored fields explicitly specified)

And this is insufficient for many needs. And there are additional features/syntaxes that would be really handy.
Case 1 : Dynamic fields ( field names are prefixed/suffixed/name-spaced)
fl=*
fl.prefix = <prefix>.*
fl.suffix = *.<suffix>
or even better
fl.ftype=<field-type>

Case 2: Field Names are explicitly namespaced by user
fl =*
fl = <regular-expression>

Implementation wise this can be achieved by firing a LukeRequest handler to resolve the fields .. We have to be carefully see its impact on document cache keys and size but for starters we can just mark the feature an experimental and disable the document cache for wildcard support.
Similarly there are a lot of cases, where user has explicitly stored huge fields for completeness sake and usually never needs it.
Currently we have includeOnly syntax in case of fl but something like
fl.exclude=<field-name|regex-on-field-name> will be immensely useful.