Behaviour of "string" parser does not match example in docs

[ktonon]

Doc for function (</>) shows:

    parsePath (s "search" </> string) location
    -- /search/cats/  ==>  Just "cats"
    -- /search/frog   ==>  Just "frog"
    -- /search/       ==>  Nothing
    -- /cats/         ==>  Nothing

But parsePath (s "search" </> string) location returns Just "" because the implementation of string is

string : Parser (String -> a) a
string =
    custom "STRING" Ok

Not sure which is correct. Assuming the docs are the desired behaviour:

{-| Parse a segment of the path as a `String`.
    parsePath string location
    -- /alice/  ==>  Just "alice"
    -- /bob     ==>  Just "bob"
    -- /42/     ==>  Just "42"
    -- /        ==> Nothing
-}
string : Parser (String -> a) a
string =
    custom "STRING" <|
        \segment ->
            if String.isEmpty segment then
                Err "string does not match empty segment"
            else
                Ok segment

Using elm-doc-test would catch this earlier.

Caught the issue while working on a PR to add doc tests. Using elm 0.18.0

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[crypticmind]

Just stumbled upon this issue

[crypticmind]

The slash is required though. This is what I tested:

> import UrlParser exposing(..)
> location = { href = "", host = "", hostname = "", protocol = "", origin = "", port_ = "", pathname = "", 

> parsePath (s "aaa" </> string) { location | pathname = "/aaa/bbb" }
Just "bbb" : Maybe.Maybe String
> parsePath (s "aaa" </> string) { location | pathname = "/aaa/" }
Just "" : Maybe.Maybe String
> parsePath (s "aaa" </> string) { location | pathname = "/aaa" }
Nothing : Maybe.Maybe String

[sethlivingston]

Stumbled on this, too. @crypticmind do you have a PR?

[crypticmind]

@sethlivingston I created #53, but @ktonon also created #43. Either of them will fix the issue. In the meantime, just use your own string parser in your routes:

string : Parser (String -> a) a
string =
  custom "STRING" <|
    \segment ->
      if String.isEmpty segment then
        Err "Empty string"
      else
        Ok segment

In my code, I'm actually validating the string isn't also blanks:

string : Parser (String -> a) a
string =
  custom "STRING" <|
    \segment ->
      if segment |> String.trim |> String.isEmpty then
        Err "Empty or blank string"
      else
        Ok segment

[ktonon]

I'm closing this issue as this project is no longer active.