tl;dr - On a Haskell project I’m working on I started with >~20 minute cold-cache builds in the worst case in my Gitlab-powered CI environment then found some small ways to improve. Very recently I decided I wasn’t satisfied with ~10 / 15 minute builds and did the laziest, least-effort steps I could find to get to <10 minute cold-cache builds (~5min best case). Check out the [TLDR][tldr] section to see the Dockerfiles and steps I took summarized.
UPDATE (02/10/2018) Don’t use HSTringTemplate… Use Ginger. You probably know Jinja2 templates already, the template structure if familiar, more robust, and the documentation is way better.
Over the last month or two, I’ve had some unexpected/weird problems building my Haskell projects on Linux – all of a sudden the project would fail to compile fairly innocuous requirements (that had up until that time compiled just fine) and I was very confused. It turns out a change to how the `
tl;dr - I added some caching to an app I’m writing in Haskell using Servant. The implementation is pretty naive, but I’ve seen some speedups (as one would expect from skipping a database access), and am glad I was able to build such a simple solution in a language as expressive as haskell. Skip to the end TLDR section to see all the code laid out!
tl/dr; I added continuous delivery to my Haskell project (after working through adding CI). The setup is somewhat convoluted, but that’s more due to personal organizational preference. This posts rambles A LOT so feel forward to skip to the end, and check out the config files that made it happen.
tl;dr I set up CI on my haskell project, it’s pretty easy if you keep calm and use Gitlab’s CI settings. I hit a few bumps in the road along the way, but you can skip to the end for the completed
tl;dr - You may not need a big robust beautifully crafted DB like Postgres every time you build an app. Sometimes SQlite is probably enough. SQLite even provides Full Text Search addons in the way of FTS3/4 and FTS5, so that’s cool too – skim through the article for code snippets on the why/how I’m using SQLite + FTS3/4.
tl;dr - I moved from server-side stored sessions provided by
Network.Wai.Session to client-side signed+encrypted session tokens provided by Wai.ClientSession for my Servant-powered webapp, it’s pretty easy, skim through to see the setup code,
/logout code that was required.
tl;dr - After a bunch of trial and error, I end up building a mostly static binary from a docker container. With hindsight it was only “mostly” static because after trying to get sendmail working from haskell code, the getProtocolByName system call was failing, pointing to the fact that there were a bunch of libraries NOT included in the executable I thought was fully static (GHC warned me) that needed to be present in the same form in the deployment container. This prompted making…
tl;dr - It’s pretty easy to use Graylog as a System.Logger backend, check out the code at the end, also if you’re interested in just regular crash-level logging with Servant, there’s some code you might like at the bottom too.