// YCombinator is not needed since tailspin supports recursion readily, but this demonstrates passing functions as parameters

templates combinator&{stepper:}
  templates makeStep&{rec:}
    $ -> stepper&{next: rec&{rec: rec}} !
  end makeStep
  $ -> makeStep&{rec: makeStep} !
end combinator

templates factorial
  templates seed&{next:}
    <=0> 1 !
    <>
      $ * ($ - 1 -> next) !
  end seed
  $ -> combinator&{stepper: seed} !
end factorial

5 -> factorial -> 'factorial 5: $;
' -> !OUT::write

templates fibonacci
  templates seed&{next:}
    <..1> $ !
    <>
      ($ - 2 -> next) + ($ - 1 -> next) !
  end seed
  $ -> combinator&{stepper: seed} !
end fibonacci

5 -> fibonacci -> 'fibonacci 5: $;
' -> !OUT::write