How to construct a macro emitting arbitrary number of possible matches?

Question

Let's say I would like to create a macro of this kind:

m(1, k) would produce:

match(k)
{
  | 1 => 2
  | _ => 0
}

m(2, k) would produce:

match(k)
{
  | 1 => 2
  | 2 => 3
  | _ => 0
}

and so on. Although construction like <[ $i => $(i + 1) ]> for the possible match is accepted, I do not know how to create match expression consisting of these. The example is of course contrived ;)

Answer 1

public macro m(to, k)
{
  def toInteger(literal)
  {
     | <[ $(i : int) ]> => i
     | _ => Message.Error(literal.Location, $"'$literal' integer literal expected"); 0;
  }

  def to = toInteger(to);

  def createCases(i) 
  {
     | i when (i > 0) => <[case: | $i => $(i + 1)  ]> :: createCases(i - 1);
     | _ => [ <[case: | _ => 0 ]> ]
  }

  <[
    match ($k)
    {
      ..$(createCases(to))
    }
  ]>
}

http://nemerle.org/Macros_tutorial#Matching_match-cases