Issue 1800 - typing error problem with using macro, switch and type parameter - haxe

[issuesbot]

[Google Issue #1800 : https://code.google.com/p/haxe/issues/detail?id=1800]
by heinz.ho...@googlemail.com, at 09/05/2013, 23:00:14
try to compile the following code. It fails with

Bug.hx:22: characters 23-30 : Unknown<0> should be {+ get : Void -> Unknown<0> }
Bug.hx:22: characters 23-30 : For function argument 'v'
Bug.hx:22: characters 4-8 : Void should be haxe.ds.Option<{+ get : Void -> Unknown<0> }>

---

package ;

import haxe.ds.Option;

using Bug.Helper;

class Helper {
    macro public static function get <T>(e:haxe.macro.Expr.ExprOf<T>):haxe.macro.Expr.ExprOf<T> return e;
    }

class Bug {
    static function test <T>(a:Array<T>) {
        var v = None; // fails
        // var v:Option<T> = None; // fails also
        for (e in a) {
            v = switch (v) {
                case Some(x): Some(x.get());
                case None: Some(e);
                }
            }
        }
    static function main () {
        test([1,2]);
        }
    }

---

without type parameter it only fails when v is not explicitly typed:

static function test (a:Array<Int>) {
    // var v = None // fails
    var v:Option<T> = None; // works
    for (e in a) {
        v = switch (v) {
            case Some(x): Some(x.get());
            case None: Some(e);
            }
        }
    }

[issuesbot]

[comment from heinz.ho...@googlemail.com, published at 09/05/2013, 23:03:40]
sorry, it should mean

var v:Option = None;

in the second example.

However i realized that it has nothing to do with macros the following example produces the same error:

package ;

import haxe.ds.Option;

using Bug.Helper;

class Helper {
    public static function get (e):T return e;
}

class Bug {
    static function test (a:Array) {
        var v:Option = None; 
        for (e in a) {
            v = switch (v) {
                case Some(x): Some(x.get());
                case None: Some(e);
            }
        }
    }
    static function main () {
        test([1,2]);
    }
}

[issuesbot]

[comment from heinz.ho...@googlemail.com, published at 09/05/2013, 23:04:56]
i'm tired ;), it should mean

class Helper {
    public static function get (e:T):T return e;
}

in the second example, but it has no influence at all.

[issuesbot]

[comment from si...@haxe.org, published at 10/05/2013, 09:16:17]
I'll have to review how context type parameters are handled.

[issuesbot]

[comment from si...@haxe.org, published at 10/05/2013, 09:51:01]
Related issue #1311.

[issuesbot]

[comment from si...@haxe.org, published at 12/05/2013, 10:56:53]
This issue was closed by revision 2fa999b.