Safe Haskell | Safe-Inferred |
---|---|

Language | Haskell2010 |

This module contains an extensible error infrastructure.

Each kind of errors gets a separate type class which encodes
a `Prism`

(roughly a getter and a constructor). The `Reader`

s, then,
have the constraints for precisely the set of errors they can return.

# Documentation

The type of errors returned by `envparse`

's `Reader`

s. These fall into 3
categories:

- Variables that are unset in the environment.
- Variables whose value is empty.
- Variables whose value cannot be parsed.

class AsUnset e where Source #

The class of types that contain and can be constructed from the error returned from parsing unset variables.

class AsEmpty e where Source #

The class of types that contain and can be constructed from the error returned from parsing variables whose value is empty.