# RAKU is a simple, fun to use and to embed scripting language. 
# The syntax resembles TCL somewhat but it's semantics are somewhat lisp like.

STATEMENTS   ←  ((STATEMENT COMMENT? / COMMENT) EOS)+
~COMMENT     ←  "#---" (!("---#").)* "---#" /  "#" (!([\r\n]+).)*
STATEMENT    ←  TERM ( OPERATOR TERM )*
TERM         ←  CALL / VALUE / BLOCK / PBLOCK / BBLOCK
CALL         ←  VALUE ARGUMENTS
BLOCK        ←  "{" EOS? STATEMENTS? "}" 
BBLOCK       ←  "[" EOS? STATEMENTS? "]"
PBLOCK       ←  "(" EOS? STATEMENT EOS? ")"
ARGUMENTS    ←  (BLOCK / PBLOCK / BBLOCK / VALUE)+ 
OPERATOR     ←  < [-+/*] / "<<" / ">>" / "<-" / "->" / "<=>" / "<=" / ">=" / "<" / ">" / 
                  ".." / "." /
                  "&&"/ "&" / "||" / "|" / "^^" / "^" / "==" / "="  > 
VALUE        ←  WORD / SYMBOL / STRING / NUMBER
STRING       ←  SYMBOL / ESCSTR / RAWSTR
# Raw string macro
RAWSM(O,C)   ← O < (!(C).)* > C
# Escaped string macro.
ESCSM(O,C)   ← O < (!(C)STRCHAR)* > C
SYMBOL       ← < ":" WORD >
ESCSTR       ← ESCSM("`", "`") / ESCSM('"', '"')
RAWSTR       ← RAWSM("'", "'") /  RAWSM('«', '»') / RAWSM('‹', '›') / RAWSM('“', '”')
STRESC1      ← "\\" [nrtfv\'\\"\[\]\\]
STRESC2      ← "\\" [0-3] [0-7] [0-7]
STRESC3      ← "\\" [0-7] [0-7]*
STRESC4      ← "\\x" [0-9a-fA-F] [0-9a-fA-F]?
STRESC5      ← "\\u" [0-9a-fA-F]+
STRNOESC     ← (!('\\\\').)
STRCHAR      ←   STRESC1 / STRESC2 / STRESC3 / STRESC4 / STRESC5 / STRNOESC    
NUMBER       ←  DECIMAL / INTEGER
DECIMAL      ← < [-+]?[0-9]+[.][0-9]+ >
INTEGER      ← < [-+]?[0-9]+ >
~EOS         ← ([ \t]*[\r\n;]+[ \t]*)+
WORD         ← < [_a-zA-Z][-_a-zA-Z0-9]* >
WHITESPACE   ← < [ \t]* >
%whitespace  ←  [ \t]*
%word        ← [a-zA-Z][-+/*a-zA-Z0-9]*
---
# Expression parsing option
%expr  = STATEMENT   # Rule to apply 'precedence climbing method' to
%binop = L =
%binop = L <- ->
%binop = L + - | ^
%binop = L * / & << >>
%binop = L && || ^^
%binop = L == <=> <= >= < >
%binop = L . ..