Lua 5 Light

It`s proposed grammar(Byson) for ( Lua 5 Light, may be ), in style @Lua 5.1 Reference Manual@

1 chunk: laststat
2 | stat;

3 block_ended: laststat
4 | stat_w_end;

6 stat_w_end: stat "end";

    7 laststat: stat "return" args
    8         | stat "return"
    9         | stat "break" "`[integral const]`"
   10         | stat "break"
   11         | stat "error" args;

12 function_def: "function" '(' parlist ')' block_ended
14 | '\\' parlist '\\' block_ended;

   16 parlist: /* empty */
   17        | "`...`"
   18        | namelist '|' "`...`"
   19        | namelist '|' Name
   20        | namelist;

21 namelist: namelist ',' Name
22 | Name;

   23 stat: /* empty */
   24     | "use" varlist       // Lua: local sin, cos = math.sin, math.cos; Lua5L: use math.sin, math.cos
   25     | stat "if" if_unmatched "else" block_ended
   27     | stat "if" if_unmatched "end"
   28     | stat "loop" stat_w_end      // Lua: "while" "true" stat_w_end
   29     | stat "while" exp stat_w_end
   30     | stat "for" namelist '=' explist stat_w_end
            // Lua: for i=1,50 do...; for i=1,20,3 do...; for k,v in pair(t) do...
            // Lua5L{as Clu, w/o 'in' & 'do'}:
                // for i = from_to(1,50) ... for i = from_to_by(1,20,3) ... for k,v = pair(t) ...
   31     | stat "repeat" stat "until" exp
   32     | stat '#' varlist '|' var '=' explist
   33     | stat '#' varlist '=' explist
   34     | stat '?' function_call
   35     | stat "local" namelist
   36     | stat "local" namelist '|' Name '=' explist
   37     | stat "local" namelist '=' explist
   38     | stat "do" block_ended
   40     | stat "yield" args
   41     | stat "yield";

43 if_unmatched: if_unmatched "elseif" if_unmatched
44 | exp "then" chunk;

46 varlist: varlist ',' var
47 | var;

48 bracket: '(' exp ')'

   49 var: Name
   50    | "self"
   51    | bracket var_omega
   52    | var var_omega
   53    | function_call var_omega;

54 var_omega: '[' exp ']'
55 | ": identifier"; // Lua: ('.' Name) / (':' Name), Lua5L: Name:Name.Name <- may be

   56 function_call: bracket args
   57              | var args
   58              | function_call args;

   59 args: '(' explist ')'
   60     | '(' ')'
   61     | '{' fieldlist '}'
   62     | '{' '}'
   63     | String
   64     | "`[integral const]`"
   65     | "`[const object]`"; // nil, false, true, number

66 explist: explist ',' exp
67 | exp;

   68 exp: _expression_
   70    | exp '`' var '`' exp /* 0 */ // Lua: var '(' exp ',' exp ')'
   71    | exp "`or`" exp /* 1 */
   72    | exp "`xor`" exp /* 1 */
   73    | exp "`and`" exp; /* 2 */

   74 _expression_: _expression_ "`==`" _expression_ /* 3, %nonassoc */
   75           | _expression_ "`~=`" _expression_ /* 3, %nonassoc */
   76           | _expression_ '>' _expression_ /* 3, %nonassoc */
   77           | _expression_ '<' _expression_ /* 3, %nonassoc */
   78           | _expression_ "`<=`" _expression_ /* 3, %nonassoc */
   79           | _expression_ "`>=`" _expression_ /* 3, %nonassoc */
   80           | _expression_ "`..`" _expression_ /* 4, %right */
   81           | _expression_ '+' _expression_ /* 5 */
   82           | _expression_ '-' _expression_ /* 5 */
   83           | _expression_ '*' _expression_ /* 6 */
   84           | _expression_ '/' _expression_ /* 6 */
   85           | _expression_ '%' _expression_ /* 6 */
   86           | '-' _expression_ /* 7 */
   87           | '+' _expression_ /* 7 */
   88           | '!' _expression_ /* 7 */
   89           | _expression_ '^' _expression_ /* 8,%right */
   90           | '$' _expression_ /* 9 */       // {len} Lua: #exp
   91           | const_exptession
   92           | function_def
   93           | bracket
   94           | function_call
   95           | var
   96           | "`...`";

   97 const_exptession: '{' fieldlist '}'
   98                 | '{' '}'
   99                 | String
100                 | "`[integral const]`"
101                 | "`[const object]`";

102 fieldlist: fieldlist ',' fieldlist
103          | '[' exp ']' '=' exp
104          | Name '=' exp
105          | exp;

A rhetorical question about: is it really necessary? - not accept. Its longe, boring question, and not rhetorical answer.

The question: Have You interesting idea about Lua syntax?

PS: PEG released, its no problem.