In many programming languages, the so-called dot-notation is commonly associated with selecting a field from a given tuple-value, record-value or object-value. In ATS, field selection can be done through either pattern matching or the use of dot-notation. For example, the following code constructs a flat tuple and also a boxed one, and then uses dot-notation to select their components:

// val tup_flat = @("a", "b") val tup_boxed = $tup("a", "b") // val-"a" = tup_flat.0 and "b" = tup_flat.1 val-"a" = tup_boxed.0 and "b" = tup_boxed.1 //

As an example of dot-notation in overloading, let us introduce a non-linear abstract type point for points in a 2-dimensional space and also declare some associated functions:

// abstype point = ptr // boxed // extern fun point_make (x: double, y: double): point // extern fun point_get_x (p: point): double and point_get_y (p: point): double // extern fun point_set_x (p: point, x: double): void and point_set_y (p: point, x: double): void //

symintr .x .y overload .x with point_get_x overload .x with point_set_x overload .y with point_get_y overload .y with point_set_y

val p0 = point_make (1.0, ~1.0) val x0 = p0.x() // point_get_x (p0) and y0 = p0.y() // point_get_y (p0) val () = p0.x := y0 // point_set_x (p0, y0) and () = p0.y := x0 // point_set_y (p0, x0)

Let us introduce a linear abstract type counter for counter objects and a few functions associated with it:

// absvtype counter = ptr // extern fun counter_make (): counter extern fun counter_free (counter): void // extern fun counter_get (cntr: !counter): int extern fun counter_incby (cntr: !counter, n: int): void //

Let us introduce the following overloading declarations:

As is expected, one can now call counter_get as follows: Similarly, one can call counter_incby as follows to increase the count stored in c0 by 1: If we revisit the previous example involving (non-linear) points, then we can see that the following code also typechecks:val p0 = point_make (1.0, ~1.0) val x0 = p0.x() // point_get_x (p0) and y0 = p0.y() // point_get_y (p0) val () = p0.x(y0) // point_set_x (p0, y0) and () = p0.y(x0) // point_set_y (p0, x0)

Please find on-line the entirety of the code presented in this chapter plus some testing code.