* Fix import resolution performance regression
Related to https://github.com/dhall-lang/dhall-haskell/issues/1511
This fixes a performance regression introduced in #1159 where `newManager`
was being called on every remote import. This fixes that by going back to
caching the `Manager` created by the first request.
This leads to *dramatic* performance improvements for import-rich packages
(like the Prelude or `dhall-kubernetes`) on the first import. For example,
here are the performance numbers for importing the Prelude for a cold cache
before and after this change:
Before:
```
$ XDG_CACHE_HOME=.cache time dhall hash <<< 'https://prelude.dhall-lang.org/package.dhall'
sha256:99462c205117931c0919f155a6046aec140c70fb8876d208c7c77027ab19c2fa
64.10 real 10.83 user 2.73 sys
```
After:
```
$ XDG_CACHE_HOME=.cache2 time dhall hash <<< 'https://prelude.dhall-lang.org/package.dhall'
sha256:99462c205117931c0919f155a6046aec140c70fb8876d208c7c77027ab19c2fa
4.39 real 0.49 user 0.15 sys
```
That's ~16x faster!
The improvement for `dhall-kubernetes` is smaller, but still significant:
Before:
```
$ XDG_CACHE_HOME=.cache3 time dhall hash <<< ~/proj/dhall-kubernetes-charts/stable/jenkins/index.dhall
sha256:04ebd960f6af331c49c3ccaedb353ac8269032b54fe0a29bd167febcd7104d4f
833.59 real 145.36 user 36.16 sys
After:
```
$ XDG_CACHE_HOME=.cache4 time dhall hash <<< ~/proj/dhall-kubernetes-charts/stable/jenkins/index.dhall
sha256:04ebd960f6af331c49c3ccaedb353ac8269032b54fe0a29bd167febcd7104d4f
381.41 real 8.41 user 1.91 sys
```
... or ~2-3x improvement.
* Fix `-f-with-http` build
* Remove unnecessary `CPP`
... as caught by @sjakobi
This updates the `dhall` package to have 100% haddock coverage and
also updates CI to enforce this going forward.
This also includes a change to deprecate the `X` type synonym, which
I noticed along the way
