# Shpadoinkle Debug

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This package exposes some useful debugging functions for tracing the state of Shpadoinkle applications as they change over time. It exposes 2 type classes currently.

```haskell
class LogJS (c :: Type -> Constraint) where
  logJS :: c a => a -> JSM ()

class LogJS c => Trapper c where
  trapper :: c a => JSContextRef -> a -> a
```

These are intended to by used with `TypeApplications`, so you can choose the means of conversion before passing to `console.log`. For example:

```haskell
main :: IO ()
main = runJSorWarp 8080 $ do
  ctx <- askJSM
  simple runParDiff initial (view . trapper @ToJSON ctx) getBody
```

Will log all state by first encoding to JSON with Aeson, then then logging with `JSON.parse` so the browser console has the nice native display. If we change it to `trapper @Show ctx` it will use the `Show` instance instead.