GHC 7.4.2 on Ubuntu Trusty

[Yitzchak Gale]

In order support some older software that we released, we need
to get a working GHC 7.4.2 on Ubuntu Trusty. We currently have
GHC 7.8.3.

The binary tarball for GHC 7.4.2 does not install on Trusty due to
multiple incompatibilities. For example, GHC requires GMP 3, but
Trusty only provides GMP >= 4. Etc.

I tried building GHC 7.4.2. from source on Trusty. But the process
won't boot from our currently installed GHC 7.8.3. The oldest
GHC binary I can get is GHC 7.6.3, which happens to be
still available from the Ubuntu distribution itself (neither the binary
tarball nor compiling from source work for GHC 7.6.3 on Trusty
either). But booting from GHC 7.6.3 won't work either.

How do I get a working GHC 7.4.2 on Trusty?

Thanks,
Yitz