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# scoped-codensity

This implements a Monad just like `Codensity` from the `kan-extensions` package, but it uses a skolem trap just like the `ST s` monad to track resources allocated in the monad.

The package wraps around different "scoped" resources that cannot escape a `scoped` block and are safely deallocated when the block is left.

## How to make your own resources safe

- for acquiring your resources:
  - use the `bracketScoped` function where possible
  - if you're using the raw `UnsafeMkScoped` constructor, make sure, the scope of your `ScopedResource` adheres to the scope you're in, by making your function return something of the shape `Scoped (s : ss) m (ScopedResource s)`
- of working with your resources:
  - if you want to use the resource only in the same scope that it was created in, your function should be of the form: `ScopedResource s -> ... -> Scoped (s : ss) m a`
  - if you want to use the resource in the same scope and scopes that are contained within the scope (this is the more common option), relate the scope of the resource to the scopes of the `Scoped` monad, by specifying `s :< ss` like so:
    `(s :< ss) => ScopedResource s -> .. -> Scoped ss m a`
- make sure that your actions are always in the `Scoped` monad and your resources always relate to the scopes that the monad is parametrized over, otherwise you might escape resources