* stuff

Sources/Extensions.swift

@@ -90,7 +90,6 @@ extension MTLVertexFormat {
 
         default: fatalError("cannot construct a vertex format for type \(t)")
         }
-
     }
 }
 

Sources/GPUDevice.swift

@@ -40,15 +40,20 @@ final class GPUDevice {
         return d
     }
 
+    func makeCommandBuffer() -> MTLCommandBuffer {
+        return commandQueue.makeCommandBuffer()!
+    }
+
     func computePipeline(name : String) -> MTLComputePipelineState {
         let f = library.makeFunction(name: name)!
         return try! device.makeComputePipelineState(function: f)
     }
 
     func makeBuffer<T>(for content: [T]) -> MTLBuffer {
+        let length = content.count * MemoryLayout<T>.size
         var cpy = content
         guard let buffer = device.makeBuffer(bytes: &cpy,
-                                             length: content.count * MemoryLayout<T>.size,
+                                             length: length,
                                              options: []) else { fatalError() }
         return buffer
     }

main/main.swift

@@ -0,0 +1,19 @@
+//
+//  main.swift
+//  main
+//
+//  Created by Adam Nemecek on 9/11/17.
+//
+
+import Foundation
+
+import MetalKit
+
+struct A {
+    let a : Int32 = 5
+    let b : Int32 = 10
+}
+
+let q = MTLVertexDescriptor(reflecting: A())
+
+