How can I implement a conditional access operator?

[geekrelief]

Thanks for replying. I created a working PR before I saw your reply. I saw the 
issue with precedence as well and mattaylor the maintainer added `.?` as an 
alternative for `?.` for higher precedence. I changed the implementation to 
`untyped` instead of using a `proc` type.

So this works: 
    
    
    template `.?`*(left, right: untyped): untyped =
      if ?left: left.right
      else:
        var res: typeof(left.right)
        res
    
    
    Run

So this works: 
    
    
    type
      Data = ref object
        val: int
      
      Obj = ref object
        data: Data
    
    var nilObj:Obj
    var objNilData = Obj()
    var obj = Obj()
    obj.data = Data()
    obj.data.val = 10
    
    ...
    
    suite "conditional access (chained)":
      test "nil check": check(nilObj.?data == nil)
      test "falsy on ref": check(nilObj.?data.?val == 0)
      test "falsy on ref": check(objNilData.?data.?val == 0)
      test "truthy on ref": check(obj.?data.?val == 10)
    
    
    Run