Add digit helper

src_v2/parser/parser_internals.nim

@@ -94,6 +94,7 @@ proc ch*(expectedChar: char): parserFnT {.inline.} =
         ))
 
 let anyCh* = ch(AllChars)
+let digit* = ch(Digits)
 
 proc str*(s: string): parserFnT {.inline.} =
   return proc(parser: Parser): ParserResult =
@@ -243,12 +244,10 @@ when isMainModule:
 
   block testParsingFunctions:
     let ch1 = ch('1')
-    let chDigits = ch(Digits)
 
     # Success
     assert testParser123.flatMap(ch1).tokensToString() == "1"
     assert testParser123.flatMap(anyCh).tokensToString() == "1"
-    assert testParser123.flatMap(chDigits).tokensToString() == "1"
     assert testParser123.flatMap(str("123")).tokensToString() == "123"
 
     # Mismatch