I use fslex and fsyacc in many of my F# programs so I find these tools very important. There are some standard syntactic sugar implemented in other yacc and lexers that greatly enhance the readability of parser specifications. I would love to see these extensions also for the F# version of these tools.

1. Allow symbolic aliases for tokens, e.g.

%token ASSIGN=":=", PLUS="+" ...

which lets you use the symbolic names in grammar rules.

2. Allow rule macros for defining common grammar rules like lists, optional elements etc. For example in the format:

%macro LIST1(a) :

| LIST1(a) a { $2 :: $1 }

| a { [$1] }

which lets use use LIST1(myterminal) in grammar rules and removes the need of all the tedious list-like grammar rules that often fills a big section of the fsyacc source.

These enhancement should be simple to implement and are also backward compatible with the current format in fsyacc. The symbolic operators are merely nice to look at but the rule macros can dramatically reduce the size of a large grammar specification.

3. Finally I wonder what happened with the very useful 'as' pattern that were present in the original ocamllex?