Support reading .a files in GHCi to reclaim some disk space

Currently, Cabal builds two code files for every libary it installs:

mbolingbroke@mb566 ~/.cabal/lib/vector-space-0.5.6/ghc-6.10.1
$ ls
.
..
Data
HSvector-space-0.5.6.o
libHSvector-space-0.5.6.a

The .a is a straight concatenation of the .o files that got built. The .o is the result of lding together all the .o files (and so has inter-object references already resolved) but is actually only used by GHCi.

If GHCi could support loading .a files then Cabal wouldn't have to build this extra .o file and we could cut the size of installed libraries almost in half.

(Or perhaps GHC could link against the .o rather than the .a, and then Cabal could stop building the .a, instead?)

[12:32] BSP_: does cabal build both .o and .a's for a library purely because ghci isn't capable of reading the .a format and loading each .o individually?
[12:33] BSP_: it seems a bit wasteful to have two copies of the code installed for each library...
[12:35] dcoutts: BSP_: that's correct
[12:35] dcoutts: in theory it's not that hard
[12:35] dcoutts: there's no real need for ghci to read the .a index, just link in everything
[12:36] arjanb left the chat room. ("bbl")
[12:36] dcoutts: the .a format is trivial
[12:36] • dcoutts has a parser
[12:36] dcoutts: and generator for that matter

Trac metadata

Trac field	Value
Version	6.10.2
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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