Syd's rules for sustainable Haskell

• Make the simplest thing you can get away with.
• Don't make things more general than you need to.
• Don't make a system distributed if that's not a hard requirement.
• Use sqlite if you can get away with not having more than one machine.
• Use postgres if you cannot get away with having only one machine.
• Solve the problem you have, not the problem you hope to have.
• Write tests first. If you can't do that, you've probably made things too complex.
• Ban dangerous functions. Think twice before introducing exceptions.
• Know about WATs
• Remove every instance that you don't use.
• Before writing an instance, write a function. Then reconsider whether you still need an instance. (You probably don't.)
• Don't write an instance if you can't use it to write generic code.
• If your instance is not law-abiding, remove it.
• Write json instances manually, and have roundtrip tests.
• Don't use lenses. You don't need them.
• Choose an automated formatter, don't argue about which one, and enforce its use.
• Choose an automated linter and enforce its use.
• Use prefix naming: data Thing = { thingField :: FieldType }
• Use as few languages extensions as you can get away with.