`let` inside a refinement type

Question

I have a Liquid Haskell refinement type that looks like this:

{-@
  addDigit ::
    c : Bool -> x : Digit -> y : Digit ->
    { v : (Bool, Digit)
    |  fst v = ((x + y + if c then 1 else 0) > 9)
    && (snd v + (if (fst v) then 10 else 0)) == (x + y + if c then 1 else 0)
    }
@-}

Is there a way morally equivalent to let-bind a name inside the refinement type, so that I can avoid writing x + y + if c then 1 else 0 twice? I.e. something like the following made-up syntax:

{-@
  addDigit ::
    c : Bool -> x : Digit -> y : Digit ->
    { v : (Bool, Digit)
    |  let z = x + y + if c then 1 else 0 
    in fst v = (z > 9)
    && (snd v + (if (fst v) then 10 else 0)) == z
    }
@-}