For another programs (that compile fine with ghc --make), I didn't
bother making the package. But I had to find out the package
dependencies by building, checking where it fails, and trying to add a
package to the dependency list. Maybe there's a better way, didn't
find it.
We do plan to fix this in the same way we resolve missing imports.
I had a look to see if I could do it when a user cabalizes the source,
but "ghc --make -v" does not include the packages automatically
loaded in its output. Instead we will need to wait for the error then
resolve it when the user presses Ctrl+R.
I looked into this for Vim's haskellmode (would also be nice for
cabal itself), never got the time to implement more than
':show packages', but perhaps this info helps you along:
- 'ghc -v -e ..' instead of 'ghc -v --make ..' avoids the temporary files
(assuming the file can be loaded by GHCi).
- GHCi's ':show packages' was intended to provide package info,
but seems to have bitrotted (you could try the undocumented
internal ':show linker' and please file a ticket for ':show packages').
- to force loading without running the code, one might have to
resort to ugly things like:
ghc -v -e 'snd(main,1)' -e ':show linker' tst.hs
- at which stage, we might as well use something like
$ ghc -v -e 'snd(main,1)' tst.hs 2>&1 | grep Load
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... *** Parser:
Loading package ffi-1.0 ... linking ... done.
Loading package ghc-paths-0.1.0.6 ... linking ... done.
Loading package array-0.3.0.1 ... linking ... done.
Loading package containers-0.3.0.0 ... linking ... done.
- for automatic package generation, one would also need
the language extensions in use (among other things);
unfortunately, the code for that in GHC stops at the
first missing extension and is not yet written in a way
that makes it easy to identify all such cases.
- ideally, one would have ghc --show-languages and
ghc --show-packages, or ghc --mk-cabal, or implement
them via GHC API.
Hth,
Claus
PS. if someone started a haskell-tools list (for cross-tool
interests in haskellmodes, ides, ghc-api clients, etc., I
would subscribe, though I can't afford the time to do
much Haskell hacking at the moment)
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