# 11-haskell-typeclasses

This example shows intermediate Haskell abstraction with a custom type class and several instances.

It includes:

- a custom `Renderable` type class,
- instances for domain types and a report wrapper,
- a small CLI that uses one shared rendering interface, and
- a test suite run by `nix flake check`.

Useful commands:

```bash
nix develop
cabal run
cabal run -- production failed 2
cabal test

nix build
./result/bin/mini-render production failed 2

nix run . -- production failed 2
nix flake check
```