I spoke too soon:

aeson induces blaze-builder & dlist -- both are pretty long term established and stable - I say include 'em both.

cgi 3001.1.8.4 induces MonadCatchIO-mtl & extensible-exceptions - this is more problematic:

extensible-exceptions hasn't been needed since GHC 7, and just reexports stuff into a different place. I don't think that should be in the platform.
MonadCatchIO-mtl is one of several approaches to re-mapping extensible exceptions into mtl. While none is settled practice yet, this one is probably a dead end as it uses the older block/unblock idiom rather than the now preferred mask idiom.

I'm planning holding cgi back to 3001.1.7.5 to avoid these two packages.

thoughts always welcome!

- Mark