Open Radar

 
Summary:
If map is used with a function returning Void, Swift crashes at runtime.

Steps to Reproduce:
1. Run code like this, either compiled or in the REPL:

    func sideEffectsFunc(arg: String) { /* do something with arg */ }
    ["a", "b"].map(sideEffectsFunc)

Expected Results:
Swift invokes sideEffectsFunc and returns an array of Void, which I’m free to ignore.

Actual Results:
The resulting program crashes while trying to run Array.map.

In compiled code (32-bit iPhone Simulator), the exact error is EXC_BAD_INSTRUCTION (code=EXC_i386_INVOP, subcode=0x0) in Swift.HeapBuffer._capacity at 0x137b26.

Notes:
The actual code in my app is:

   rowViews.map(addSubview)

Which is the second-coolest thing I’ve written in this app so far. (The coolest is the use of reduce() to connect rows and columns of views with repeating patterns of layout constraints.) I hope this idiom, or something very similar, becomes officially supported—it’d be a shame to write a whole for loop when this elegant functional construct is available instead.