Module demo.lambdamatchbind.

Define User has id, name.

Rule greetUser given user, prefix, produce:
  Let f be function with value, produce:
    Match value:
      When User(id, name), Return Text.concat(prefix, name).
      When other, Return prefix.
  Return f(user).

Rule posOrZero given count, produce:
  Let sel be function with value, produce:
    If value greater than 0
      Return value.
    Otherwise
      Return 0.
  Return sel(count).