EVP-0.1: Environment Variable Parser

Safe Haskell	Safe-Inferred
Language	GHC2021

EVP

Contents

Parsers
Runner
Logger
Advanced

Synopsis

type Name = String
data Error
- = Missing Name
- | ParseError Name String String
- | CustomError String
data Scan a
data Var a = Var {
- name :: Name
- defaultValue :: Maybe a
- metavar :: Maybe String
}
string :: (IsString a, Show a, Typeable a) => Var a -> Scan a
yaml :: forall a. (Show a, Typeable a, FromJSON a, ToJSON a) => Var a -> Scan a
parse :: Show a => Var a -> (String -> Either String a) -> Scan a
secret :: Scan a -> Scan a
group :: String -> Scan a -> Scan a
defaultsTo :: Var a -> a -> Var a
data Settings = Settings {
- parseLogger :: GroupStack -> Name -> String -> IO ()
- errorLogger :: GroupStack -> Error -> IO ()
- unusedLogger :: Name -> Maybe (IO ())
- pedantic :: Bool
- helpFlag :: Maybe Name
}
def :: Default a => a
scan :: Scan a -> IO a
scanWith :: Settings -> Scan a -> IO a
enumerate :: Scan a -> [Name]
help :: Scan a -> String
type GroupStack = [String]
renderError :: Error -> String
assumePrefix :: String -> Name -> Maybe (IO ())
obsolete :: [Name] -> Name -> Maybe (IO ())
modifyError :: (Error -> Error) -> Scan a -> Scan a

Documentation

type Name = String Source #

data Error Source #

Constructors

Missing Name
ParseError Name String String
CustomError String

Instances

Instances details

Show Error Source #
Instance details Defined in EVP.Internal Methods showsPrec :: Int -> Error -> ShowS # show :: Error -> String # showList :: [Error] -> ShowS #

Parsers

data Scan a Source #

Instances

Instances details

Applicative Scan Source #
Instance details Defined in EVP.Internal Methods pure :: a -> Scan a # (<>) :: Scan (a -> b) -> Scan a -> Scan b # liftA2 :: (a -> b -> c) -> Scan a -> Scan b -> Scan c # (>) :: Scan a -> Scan b -> Scan b # (<*) :: Scan a -> Scan b -> Scan a #
Functor Scan Source #
Instance details Defined in EVP.Internal Methods fmap :: (a -> b) -> Scan a -> Scan b # (<$) :: a -> Scan b -> Scan a #

data Var a Source #

Constructors

Var
Fields name :: Name defaultValue :: Maybe a metavar :: Maybe String

Instances

Instances details

Typeable a => IsString (Var a) Source #
Instance details Defined in EVP Methods fromString :: String -> Var a #
Show a => Show (Var a) Source #
Instance details Defined in EVP Methods showsPrec :: Int -> Var a -> ShowS # show :: Var a -> String # showList :: [Var a] -> ShowS #
Eq a => Eq (Var a) Source #
Instance details Defined in EVP Methods (==) :: Var a -> Var a -> Bool # (/=) :: Var a -> Var a -> Bool #

string :: (IsString a, Show a, Typeable a) => Var a -> Scan a Source #

Obtain the environment variable.

yaml :: forall a. (Show a, Typeable a, FromJSON a, ToJSON a) => Var a -> Scan a Source #

Parse the environment variable as a YAML value.

parse :: Show a => Var a -> (String -> Either String a) -> Scan a Source #

Parse the environment variable with a custom parser.

secret :: Scan a -> Scan a Source #

Disable logging of parsed values.

group :: String -> Scan a -> Scan a Source #

Give a name to a group of parsers.

defaultsTo :: Var a -> a -> Var a infixl 1 Source #

Provide a default value.

Runner

data Settings Source #

Constructors

Settings
Fields parseLogger :: GroupStack -> Name -> String -> IO () errorLogger :: GroupStack -> Error -> IO () unusedLogger :: Name -> Maybe (IO ()) pedantic :: Bool exit on warning helpFlag :: Maybe Name when an environment varialbe with this name is set, print the help message and exit

Instances

Instances details

Default Settings Source #
Instance details Defined in EVP Methods def :: Settings #

def :: Default a => a #

The default value for this type.

scan :: Scan a -> IO a Source #

Parse environment variables with the default settings.

scanWith :: Settings -> Scan a -> IO a Source #

Parse environment variables with custom settings.

enumerate :: Scan a -> [Name] Source #

Enumerate the names of the variables it would parse.

help :: Scan a -> String Source #

Display the list of environment variables and their default values in the dotenv format.

Logger

type GroupStack = [String] Source #

renderError :: Error -> String Source #

assumePrefix :: String -> Name -> Maybe (IO ()) Source #

Custom logging function for unusedLogger. assumePrefix p prints a warning for each unused environment variable prefixed by p.

obsolete :: [Name] -> Name -> Maybe (IO ()) Source #

obsolete names prints a warning if any of the names is set but not used.

Advanced

modifyError :: (Error -> Error) -> Scan a -> Scan a Source #