Safe Haskell	Safe-Inferred
Language	Haskell2010

Env.Internal.Error

Description

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

Synopsis

data Error
- = UnsetError
- | EmptyError
- | UnreadError String
class AsUnset e where
- unset :: e
- tryUnset :: e -> Maybe ()
class AsEmpty e where
- empty :: e
- tryEmpty :: e -> Maybe ()
class AsUnread e where
- unread :: String -> e
- tryUnread :: e -> Maybe String

Documentation

data Error Source #

The type of errors returned by envparse's Readers. These fall into 3 categories:

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

Constructors

UnsetError
EmptyError
UnreadError String

Instances

Instances details

Show Error Source #
Instance details Defined in Env.Internal.Error Methods showsPrec :: Int -> Error -> ShowS # show :: Error -> String # showList :: [Error] -> ShowS #
AsEmpty Error Source #
Instance details Defined in Env.Internal.Error Methods empty :: Error Source # tryEmpty :: Error -> Maybe () Source #
AsUnread Error Source #
Instance details Defined in Env.Internal.Error Methods unread :: String -> Error Source # tryUnread :: Error -> Maybe String Source #
AsUnset Error Source #
Instance details Defined in Env.Internal.Error Methods unset :: Error Source # tryUnset :: Error -> Maybe () Source #
Eq Error Source #
Instance details Defined in Env.Internal.Error Methods (==) :: Error -> Error -> Bool # (/=) :: Error -> Error -> Bool #

class AsUnset e where Source #

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

Methods

unset :: e Source #

tryUnset :: e -> Maybe () Source #

Instances

Instances details

AsUnset Error Source #
Instance details Defined in Env.Internal.Error Methods unset :: Error Source # tryUnset :: Error -> Maybe () Source #

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.

Methods

empty :: e Source #

tryEmpty :: e -> Maybe () Source #

Instances

Instances details

AsEmpty Error Source #
Instance details Defined in Env.Internal.Error Methods empty :: Error Source # tryEmpty :: Error -> Maybe () Source #

class AsUnread e where Source #

The class of types that contain and can be constructed from the error returned from parsing variable whose value cannot be parsed.

Methods

unread :: String -> e Source #

tryUnread :: e -> Maybe String Source #

Instances

Instances details

AsUnread Error Source #
Instance details Defined in Env.Internal.Error Methods unread :: String -> Error Source # tryUnread :: Error -> Maybe String Source #