sexpr-0.2.0: S-expression printer and parser Source code Contents Index

Codec.Sexpr

Contents Basics Hinted Atoms Character predicates to support encoding Transformations String printers ShowS printers Doc pretty printers Put binary printers Parsers

Description

A Sexpr is an S-expressionin the style of Rivest's Canonical S-expressions. Atoms may be of any type, but String and ByteString have special support. Rivest's implementation of S-expressions is unusual in supporting MIME type hints for each atom. See http:people.csail.mit.edurivestSexp.txt

Synopsis

data Sexpr s isAtom :: Sexpr a -> Bool isList :: Sexpr a -> Bool atom :: a -> Sexpr a list :: [Sexpr a] -> Sexpr a unAtom :: Sexpr s -> s unList :: Sexpr s -> [Sexpr s] hintedAtom :: String -> a -> Sexpr a hint :: Sexpr a -> Maybe String defaultHint :: String isTokenChar :: Char -> Bool isInitialTokenChar :: Char -> Bool isQuoteableChar :: Char -> Bool fold :: (Sexpr t -> Sexpr t) -> Sexpr t -> Sexpr t canonicalString :: Sexpr String -> String basicString :: Sexpr String -> String advancedString :: Sexpr String -> String canonical :: Sexpr String -> ShowS basic :: Sexpr String -> Doc advanced :: Sexpr String -> Doc putCanonical :: Sexpr String -> Put putCanonicalBS :: Sexpr ByteString -> Put readSexpr :: Read a => String -> Sexpr a readSexprString :: String -> Sexpr String readCanonicalSexprString :: String -> Sexpr String advancedSexpr :: ReadP (Sexpr String) canonicalSexpr :: ReadP (Sexpr String)

Basics

data Sexpr s Source

Instances Functor Sexpr Traversable Sexpr Foldable Sexpr Eq s => Eq (Sexpr s) Read s => Read (Sexpr s) Show (Sexpr String) Show s => Show (Sexpr s) Arbitrary a => Arbitrary (Sexpr a)

isAtom :: Sexpr a -> Bool Source

A predicate for identifying atoms, whether or not they have explicit hints.

isList :: Sexpr a -> Bool Source

A predicate for recognizing lists.

atom :: a -> Sexpr a Source

Construct an atom.

list :: [Sexpr a] -> Sexpr a Source

Construct a list.

unAtom :: Sexpr s -> s Source

Extract the content of an atom, discarding any MIME type hint.

unList :: Sexpr s -> [Sexpr s] Source

Extract the sub-S-expressions of a List. If all you intend to do is traverse or map over that list, the Functor instance of S-expressions may work just fine.

Hinted Atoms

hintedAtom :: String -> a -> Sexpr a Source

Construct an atom with a MIME type hint. hintedAtom defaultHint == atom

hint :: Sexpr a -> Maybe String Source

Extract the hint of an atom. Lists do not have hints, but all atoms have hints.

defaultHint :: String Source

Any atom whose hint is not specified is assumed to be text/plain; charset=iso-8859-1. This is that default value.

Character predicates to support encoding

isTokenChar :: Char -> Bool Source

Tokens may internally contain any of the characters legitimate to begin tokens, or any numeral.

isInitialTokenChar :: Char -> Bool Source

Tokens may begin with any alphabetic character or the characters in -./_:*+= ;

isQuoteableChar :: Char -> Bool Source

Only token characters and spaces don't need to be escaped when shown in the quoted syntax.

Transformations

fold :: (Sexpr t -> Sexpr t) -> Sexpr t -> Sexpr t Source

fold f s applies f to each sub-S-expression of s, from each leaf to the root. f need not preserve the shape of s, in contrast to the shape-preserving Traversable instance.

String printers

canonicalString :: Sexpr String -> String Source

basicString :: Sexpr String -> String Source

advancedString :: Sexpr String -> String Source

ShowS printers

canonical :: Sexpr String -> ShowS Source

Doc pretty printers

basic :: Sexpr String -> Doc Source

advanced :: Sexpr String -> Doc Source

Put binary printers

putCanonical :: Sexpr String -> Put Source

putCanonicalBS :: Sexpr ByteString -> Put Source

Parsers

readSexpr :: Read a => String -> Sexpr a Source

Read a Sexpr a using the Read instance for a. The Sexpr may be in any encoding: Canonical, Basic, or Advanced.

readSexprString :: String -> Sexpr String Source

Read a Sexpr String in any encoding: Canonical, Basic, or Advanced.

readCanonicalSexprString :: String -> Sexpr String Source

Read a Sexpr String in canonical encoding.

advancedSexpr :: ReadP (Sexpr String) Source

canonicalSexpr :: ReadP (Sexpr String) Source

For some applications it is wise to accept only very carefully specified input. This is useful when you know you are receiving exactly a Canonical S-Expression. It will read only a Canonical S-expression (and optional terminating NUL), but not the Basic or Advanced encodings.

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