Text.Derp

Represents both a formal context-free language and the reduction of a member of that language to a value of type a.

Alternation.

Concatenation.

Reduction.

Null-parse extraction.

Terminal.

Epsilon/empty-string.

The empty language.

The main derivative function.

The optimization step of the algorithm.

Extract the parse-null set of a parser.

The number of compact steps that usually keeps a parser constant in size while parsing.

A specified number of compactions.

Derivation followed by a specified number of compactions.

Parse using a specified number of intermediate compactions.

Derivation followed by the default number of compactions.

Parse using the default number of intermediate compactions. This is the main parsing function. Examples:

let e =     ter "num"
        <|> e <~> ter "+" <~> e ==> (\(x1,(o,x2)) -> "(" ++ x1 ++ o ++ x2 ++ ")")
in runParse e [Token "num" "1", Token "+" "+", Token "num" 3", Token "+" "+", Token "num" "5"]

evaluates to:

Set.fromList ["((1+3)+5)", "(1+(3+5))"]

let e =     ter "num" ==> read 
        <|> e <~> ter "+" <~> e ==> (\(x1,(_,x2)) -> x1 + x2)
in runParse e [Token "num" "1", Token "+" "+", Token "num" 3", Token "+" "+", Token "num" "5"]

evaluates to:

Set.fromList [9]