Linear component is abandoned ...

[aditya siram]

Hi,
I have the following simplified version of assiging to a stack variable and am getting the following error:

"linear component of the following type is abandoned: [S2Eapp(S2Ecst(option_vt0ype_bool_vtype); S2Eapp(S2Ecst(g0int_t0ype); [1]), S2Evar(b$8622$8623(14297)))]"

I searched around and the only reference I see to this error is about using a global variable in a function scope.

Any help is appreciated.

Thanks!
-deech

extern fun add1(
  n : Option_vt(int)
) : Option_vt(int)

implement add1(n) =
  let
    fun add1_( n:Option_vt(int), res: &Option_vt(int) >> Option_vt(int) ) : void =
      case+ n of
        | ~Some_vt(i) => res := Some_vt(i+1)
        | ~None_vt() => ()
    var res : Option_vt(int) = None_vt()
    val () = add1_(n,res)
  in
    res
  end

[Artyom Shalkhakov]

Hi Aditya,

I guess you will need to free it?

пн, 28 мая 2018 г., 7:19 aditya siram <aditya...@gmail.com>:

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[aditya siram]

In my haste I didn't include the line number of the error but it points to 'res := Some_vt(i+1)'.

[Artyom Shalkhakov]

Indeed, in this case, the old value of the mutable variable is abandoned.

You could free res first, and then assign. 

пн, 28 мая 2018 г., 7:37 aditya siram <aditya...@gmail.com>:

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[Hongwei Xi]

Or you can do something like:

implement
add1(n) =
let
  fun add1_( n: Option_vt(int), res: &Option_vt(int)? >> _ ) : void =
  case+ n of
  | ~None_vt() => res := None_vt()

  | ~Some_vt(i) => res := Some_vt(i+1)

  var res : Option_vt(int)?

  val () = add1_(n,res)
in
  res
end

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[aditya siram]

Awesome, thanks! Yet again my instincts to always initialize a variable lead me astray in ATS. :)

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