[ANN] Tricorder 0.2.0.0

Announcements
1

Tricorder v0.2.0.0

Tricorder 0.2.0.0 is out, bringing you “eval comments”, a nicer tricorder source, a “restart” keybind and some nice fixes for those of you with a single-package repo.

The full change log is available at Tricorder’s repo.

Eval comments

eval-comment-simple
eval-comment-simple572×182 11.7 KB

Drop an expression into a specially-marked comment anywhere in a module, and Tricorder will evaluate it against that module’s top-level bindings every time the build succeeds — showing you the result right there, without opening cabal repl or copy-pasting code into GHCi.

There are three ways to write one.

Single-line, for quick checks:

-- $> 2 + 2

Multi-line, in a line comment, for expressions that don’t fit on one line:

-- $$>
-- someFunc 12
-- >> someOtherFunc
-- <$$

Block eval comment, the same idea inside a {- -} block, which some people find more ergonomic to write:

{- $$>
someFunc 12
>> someOtherFunc
<$$ -}

All three forms are evaluated in the context of the module they live in, so you can freely reference any top-level function or value defined there — handy for sanity-checking a helper function or eyeballing a data structure while you edit, or maybe even sending off a quick test for something you’re working on. Any expression which can be evaluated by GHCi can be used!

Results show up in two places:

  • In the TUI, press e to open the eval comments view. Each comment is listed with its file, line number, the expression, and the evaluated result (or a “Running…” indicator while it’s still evaluating).
  • On the command line, run tricorder eval-comments to print all eval comments and their results for the current build. Add --wait to block until the in-progress build finishes, and/or --json for structured output.

Source lookup from source distribution tarballs

Previously, tricorder source would use ghc-pkg to pick out and parse the Haddock HTML generated for whichever module you specified. This proved to be problematic in two main ways:

  1. Parsing HTML can be tricky.
  2. The HTML produced by Haddock is inconsistent between Cabal versions.

In Tricorder 0.2.0.0, tricorder source fetches the actual source code from the source distribution tarball, and parses out the relevant parts from there instead.

Tricorder utilizes cabal’s global sdist cache, fetching packages as needed. This means more accurate sources, and tricorder source even works for packages that do not have any generated Haddock HTML.

Other notable mentions

  • Restart the daemon from the TUI. Press R (rebindable, like every other key in Tricorder) to restart the daemon without leaving the TUI. It reconnects automatically as soon as the new daemon is ready.
  • Print the full log path. tricorder log --print-path prints the path to the current repo’s Tricorder log file, so you can tail -f it or point another tool at it without hunting it down manually.
  • Fix for <no location info> in certain single-package repos. Single-package repos no longer show an empty diagnostics list in certain cases. If you experienced that cabal repl showed compilation errors, but tricorder ui just showed <no location info>, this might do the trick for you.
  • Excessive resource usage when cabal fails on startup. The build no longer gets stuck looping after a startup failure. For example, if you forgot to nix develop or direnv allow to bring cabal into your PATH, Tricorder’s daemon would just loop infinitely as it attempted to use cabal, bloating its logs and eating at your processor time. But this is no more!

Give it a try! Get it either on Hackage or as a binary download on GitHub.

12 Likes
2

Tricorder 0.2.0.1 was just released with some fixes for stack users and multi-package cabal projects!

Get it on GitHub or on Hackage!

3 Likes