propagating inputs in ghc-* packages

[Ricardo Wurmus]

Hi Guix,

I’m in the middle of upgrading our Haskell packages.  (Actually, I’m
just yak shaving.  I need “pandoc-citeproc” for “r-knitr”…)

I noticed that upgrading Haskell packages is a pain in the neck because
of propagated inputs.  It seems that not all packages have fully
declared dependencies and just work accidentally because of propagated
inputs of a related package.  This also makes upgrades more difficult
because I can get substitutes from Hydra that depend on older versions
of some Haskell packages.

It looks like Haskell binaries actually embed references to other
Haskell packages, so I’m not sure we actually need to propagate anything
at all.  Could someone please confirm this?

~~ Ricardo