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[Radu Mereuta <headness13 AT gmail.com>]

Hi Ömer,

Try using List{Test,""}, without the space inside the separation terminal.

The problem lays with SDF, the parser that we are using in K. Space is part of the layout definition (whitespaces that separate tokens in the grammar) and sometimes it has problems handling spaces, eol... inside terminals.

If you use the list without the space, you will get a similar grammar for your language. Since Ids will match in a greedy way, the input `[a b]` will parse the same with both grammars. In your original grammar the space between the 'a' and 'b' should go to the list separator, and in the second grammar, the space would parse as layout, and will automatically be discarded when creating the AST.

I will discuss this with the rest of the group and negotiate a warning message that disallows whitespace inside terminals.

Radu

K developer

On Fri, Sep 6, 2013 at 11:31 PM, Ömer Sinan Ağacan <omeragacan AT gmail.com> wrote:

Dear K users,


This simple K program demonstrates a feature that works in an older
version K framework but fails with latest version:


    module TEST-SYNTAX

      syntax Lst ::= List{Test, " "}

      syntax Test ::= Id
                   | "[" Lst "]"

    endmodule

    module TEST

      imports TEST-SYNTAX

    endmodule


This compiles fine with both old and latest versions .. The problem is
it doesn't parse this simple program `[a b]` in latest version(fails
with "Critical: Parse error: Syntax error near unexpected character
'b'")

Anyone has ideas on this?

Thanks.


---
Ömer Sinan Ağacan
http://osa1.net

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