Indeed, the grammar does not admit "1*2/3" as a sentence ...
Huh? Why not? "1 * 2 / 3" should match factor "*" factor "/" factor. Remember that { } is repetition, so it should be able to handle such term.
expression ::= term | term "+" expression term ::= factor | factor "*" term factor ::= constant | variable | "(" expression ")"
Oh, left recursion. Well, it should be easy to transform: expression ::= term | moreTerm term ::= factor | moreFactor moreTerm ::= term "+" expression factor ::= constant | variable | "(" expression ")" moreFactor := factor "*" term correct? -- View this message in context: http://www.nabble.com/Expression-parsing-problem-tp23610457p23611617.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.