Re: [Haskell-cafe] Recursive attoparsec

On 2016-10-05 08:32 AM, Lian Hung Hon wrote:

Dear cafe,

Given

data Expression = ExpToken String | ExpAnd Expression Expression

How to write an attoparsec parser that parses this example:

"a" and "b" and "c"

into

ExpAnd (ExpToken "a") (ExpAnd (ExpToken "b") (ExpToken "c"))?

You can use recursion at Haskell level: expParser = do left <- ExpToken <$> stringLiteral (string "|" *> (ExpAnd left <$> expParser) <|> pure left)