How to parse a string value using FParsec

Question

How do I parse a simple string out of another string. In the FParsec Tutorial there is the following code given: ``` let str s = pstring s let floatBetweenBrackets = str "[" >>. pfloat .>> str "]" ``` I don't want to parse a float between backets but more a string within an expression. Sth. Like: `Location := LocationKeyWord path EOL` Given a helper function ``` let test p s = match run p s with | Success(result,_,_) -> printfn "%A" result | Failure(message,_,_) -> eprintfn "%A" message ``` And a parser-function: `let pLocation = ...` When I call `test pLocation "Location /root/somepath"` It should print `"/root/somepath"` My first attempt was to modify the tutorial code as the following: ``` let pLocation = str "Location " >>. str ``` But this gives me an error: ``` Error 244 Typeerror. Expected: Parser<'a,'b> Given: string -> Parser The type CharStream<'a> doesn't match with the Type string ```

Accepted Answer

`str` doesn't work for your path because it is designed to match/parse a constant string. `str` works well for the constant `"Location "` but you need to provide a parser for the path part too. You don't specify what that might be so here is an example that just parses any characters.

```
let path = manyChars anyChar
let pLocation = str "Location " >>. path
test pLocation "Location /root/somepath"
```

You might want to a different parser for the path, for example this parses any characters until a newline or end of file so that you could parse many lines.

```
let path = many1CharsTill anyChar (skipNewline <|> eof)
```

You could make other parsers that don't accept spaces or handle quoted paths, etc.

How to parse a string value using FParsec

Solution

Problem