Language.Nix.Identifier

Documentation

data Identifier

Identifiers in Nix are essentially strings. They can be constructed (and viewed) with the ident isomorphism. For the sake of convenience, Identifiers are an instance of the IsString class.

Reasonable people restrict themselves to identifiers of the form [a-zA-Z_][a-zA-Z0-9_'-]*, because these don't need quoting. The methods of the Text class can be used to parse and pretty-print an identifier with proper quoting:

>>> pPrint (ident # "test")
test
>>> pPrint (ident # "foo.bar")
"foo.bar"

\str -> Just (ident # str) == parseM "Ident" (quote str)

\i -> Just (i :: Identifier) == parseM "Ident" (prettyShow i)

Instances

Eq Identifier

Defined in Language.Nix.Identifier

Methods

(==) :: Identifier -> Identifier -> Bool

(/=) :: Identifier -> Identifier -> Bool

Ord Identifier

Defined in Language.Nix.Identifier

Methods

compare :: Identifier -> Identifier -> Ordering

(<) :: Identifier -> Identifier -> Bool

(<=) :: Identifier -> Identifier -> Bool

(>) :: Identifier -> Identifier -> Bool

(>=) :: Identifier -> Identifier -> Bool

max :: Identifier -> Identifier -> Identifier

min :: Identifier -> Identifier -> Identifier

Show Identifier

Defined in Language.Nix.Identifier

Methods

showsPrec :: Int -> Identifier -> ShowS

show :: Identifier -> String

showList :: [Identifier] -> ShowS

IsString Identifier

Defined in Language.Nix.Identifier

Methods

fromString :: String -> Identifier

Generic Identifier

Defined in Language.Nix.Identifier

Associated Types

type Rep Identifier :: Type -> Type

Methods

from :: Identifier -> Rep Identifier x

to :: Rep Identifier x -> Identifier

Arbitrary Identifier

Defined in Language.Nix.Identifier

Methods

arbitrary :: Gen Identifier

shrink :: Identifier -> [Identifier]

CoArbitrary Identifier

Defined in Language.Nix.Identifier

Methods

coarbitrary :: Identifier -> Gen b -> Gen b

NFData Identifier

Defined in Language.Nix.Identifier

Methods

rnf :: Identifier -> ()

HasParser Identifier

Defined in Language.Nix.Identifier

Methods

parser :: CharParser st input m Identifier

Pretty Identifier

Defined in Language.Nix.Identifier

Methods

pPrintPrec :: PrettyLevel -> Rational -> Identifier -> Doc

pPrint :: Identifier -> Doc

pPrintList :: PrettyLevel -> [Identifier] -> Doc

type Rep Identifier

Defined in Language.Nix.Identifier

type Rep Identifier = D1 (MetaData "Identifier" "Language.Nix.Identifier" "language-nix-2.2.0-4V8HiyuJODaH1hiGHTNPvO" True) (C1 (MetaCons "Identifier" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 String)))

ident :: Iso' Identifier String

An isomorphism that allows conversion of Identifier from/to the standard String type via review.

\str -> fromString str == ident # str

\str -> set ident str undefined == ident # str

\str -> view ident (review ident str) == str

quote :: String -> String

Helper function to quote a given identifier string if necessary.

>>> putStrLn (quote "abc")
abc
>>> putStrLn (quote "abc.def")
"abc.def"

needsQuoting :: String -> Bool

Checks whether a given string needs quoting when interpreted as an Identifier. Simple identifiers that don't need quoting match the regular expression ^[a-zA-Z_][a-zA-Z0-9_'-]*$.

parseSimpleIdentifier :: CharParser st tok m Identifier

Parsec parser for simple identifiers, i.e. those that don't need quoting.

parseQuotedIdentifier :: CharParser st tok m Identifier

ReadP parser for quoted identifiers, i.e. those that do need quoting.