A tool for pretty-printing structured text – e.g. JSON, or Haskell data types. Especially handy for types with broken Show instances (like UTCTime or UUID).

Install it from Hackage or use the online demo:


Do you have an example?

Sure! Try pretty-printing this sample (or just click on it):

Resource {resourceValue=User {userId=73552fc4-e181-463e-b8a9-2557e9a3aba4, userCreatedAt=2019-02-18 20:56:24.265489 UTC, userName="Artyom", userPassScrypt=<omitted>}, resourceHash=ACBD18DB4CC2F85CEDEF654FCCC4A4D8}

What about existing tools?

All existing tools that we know of fail on broken Show instances, except for pretty-simple, which has its own problems (e.g. bugs in the parser). It's nice to have something more robust.

It doesn't work on my input!

Please file an issue.

I haven't found any issues but I still want to be helpful.

That's unexpected, but delightful. You can help by: