The pattern class even

even.sjs

macro even {
  function (stx) {   /* stx is an array of syntax objects */
    console.log(stx);
    var name_stx  = stx[0];
    var arg  = stx[1];
    var val  = arg.token.value;
    var res = ( ((val%2)==0) ? [makeValue(true,name_stx)] : false );  
    if (res) return { result: [stx[1]],   
                      rest:   stx.slice(2) }
    else     return false }} 

macro isAllEven {
  case { _ ($e:even (,) ...) }
    => { return #{["yes",$e(,)...]} }
  case { _ ($e (,) ...) }
    => { return #{["no", $e(,)...]} } }

"----------------";
isAllEven();
isAllEven(2,4,6);
"----------------";
isAllEven(2,5,6);
isAllEven("x",5,6);