The (default) type of an array literal and CArray vs Array distinction

[jstasiak]

• Kit version: ad8de26
• OS/Platform: not relevant

I wanted to pass an Array to a function and tried to use an array literal:

function fun(a: Array[Int]) {
}

function main() {
    fun([1, 2, 3]);
}

It doesn't work right now:

% kitc test.kit
[2018-11-03 18:01:51.303552] ===> parsing and building module graph
[2018-11-03 18:01:51.322517] ===> processing C includes
[2018-11-03 18:01:51.535590] ===> resolving module types
[2018-11-03 18:01:51.556841] ===> typing module content
----------------------------------------
Error: ./test.kit:5: Function arg types must match the function's declaration:

  @./test.kit:5:9-17
       5        fun([1, 2, 3]);
                    ^^^^^^^^^

    Expected type:  kit.array.Array[Int]
      Actual type:  kit.common.CArray[Int8, $3]

[2018-11-03 18:01:51.601764] ===> total time: 0.297389s
[2018-11-03 18:01:51.602297] ERR: compilation failed (1 errors)

Doing an explicit cast doesn't work either:

% kitc test.kit
[2018-11-03 18:02:44.750964] ===> parsing and building module graph
[2018-11-03 18:02:44.772141] ===> processing C includes
[2018-11-03 18:02:45.005430] ===> resolving module types
[2018-11-03 18:02:45.026562] ===> typing module content
----------------------------------------
Error: ./test.kit:5: Invalid cast: kit.common.CArray[Int8, $3] as kit.array.Array[Int]

  @./test.kit:5:9-31
       5        fun([1, 2, 3] as Array[Int]);
                    ^^^^^^^^^^^^^^^^^^^^^^^

[2018-11-03 18:02:45.068829] ===> total time: 0.317073s
[2018-11-03 18:02:45.069523] ERR: compilation failed (1 errors)

I've been wondering - maybe it should be possible?

[bendmorris]

Known limitation right now. Currently array literals are typed as CArrays. I'm planning on handling this using rewrite rules in the future - a type will be able to define a rule that turns a literal into an instance of that type.