System.Envy

Classes

class FromEnv a where

FromEnv Typeclass

Methods

fromEnv :: Parser a

class Show a => ToEnv a where

ToEnv Typeclass

Methods

toEnv :: a -> EnvList a

class (Read a, Show a) => Var a where

Class for converting to / from an environment variable

Methods

toVar :: a -> String

fromVar :: String -> Maybe a

Instances

Var Bool

Var Double

Var Int

Var Int8

Var Int16

Var Int32

Var Int64

Var Integer

Var Word8

Var Word16

Var Word32

Var Word64

Var String

Var ByteString

Var ByteString

Var Text

Var Text

Var UTCTime

Var Day

data EnvList a

EnvList type w/ phanton

Instances

Show (EnvList a)

Functions

decodeEnv :: FromEnv a => IO (Either String a)

Environment retrieval with failure info

decode :: FromEnv a => IO (Maybe a)

Environment retrieval (with no failure info)

showEnv :: IO ()

Env helper

setEnvironment :: EnvList a -> IO (Either String ())

Set environment via a ToEnv constrained type

setEnvironment' :: ToEnv a => a -> IO (Either String ())

Set environment directly using a value of class ToEnv

unsetEnvironment :: EnvList a -> IO (Either String ())

Unset Environment from a ToEnv constrained type

makeEnv :: ToEnv a => [EnvVar] -> EnvList a

smart constructor, Environment creation helper

env :: forall a. (Typeable a, Var a) => String -> Parser a

Environment variable getter

envMaybe :: forall a. (Typeable a, Var a) => String -> Parser (Maybe a)

Maybe parser

(.=) :: Var a => String -> a -> EnvVar

Infix environment variable setter this is a smart constructor for producing types of EnvVar

(.!=) :: forall a. (Typeable a, Var a) => Parser (Maybe a) -> a -> Parser a

For use with (.:?) for providing default arguments