Problem using language tag in value set

Date: Sun, 14 May 2017 16:57:31 +0300
From: Janis Kajaks <janis.kajaks@gmail.com>
To: public-shex@w3.org
Subject: ShExC schema generator tool for evaluation
Archived-At: <http://www.w3.org/mid/CADt6OBMnKLLyfiPCRU+0dV0=wtavFpeXPyASxhdj+qrJAd-hWw@mail.gmail.com>

Hello,

I'm a bachelor program student from Faculty of Computing, University
of Latvia, and I'm preparing a bachelor's work on subject :RDF data
validation using data shapes". The theoretical part includes analyses
of SHACL and ShEx languages that are used for data shapes and
validation, while in the practical part I've decided to create a tool
that can automatically generate ShExC schemas based on the given RDF
data samples: http://bakalauradarbs.azurewebsites.net/ . It means that
if you have RDF data that you already know is valid, you don't have to
write schemas manually to check if other similar data is valid as
well. The tool is still in the development process, therefore I would
appreciate, if you could find some time, test its current
possibilities, and give me your opinions and suggestions. Detailed
instructions on how to use the tool you can find in section "About",
but the start is very simple - you can select some sample data for
input and let the tool do its job.

In order to test the tool, I used this online validator:
http://rawgit.com/shexSpec/shex.js/master/doc/shex-simple.html and I
found one test case which was a bit confusing - in ShEx primer
(http://shex.io/shex-primer/index.html#value-sets ) it's said that you
can use IRIs, literals or language tags for value sets, and a value
set with language tag could look something like this:

my:IssueShape {
  ex:label [@en]
}

But unfortunately it does not work in the chosen validator, it works
only if I append a tilde like this:

my:IssueShape {
  ex:label [@en~]
}

Could you, please, comment on why it works like this?
shexSpec / primer

Problem using language tag in value set #6
