diff --git a/glfw-vulkan/scratch/defer.zig b/glfw-vulkan/scratch/defer.zig
new file mode 100644
index 0000000..157d8d8
--- /dev/null
+++ b/glfw-vulkan/scratch/defer.zig
@@ -0,0 +1,11 @@
+const std = @import("std");
+
+pub fn main() !void {
+    var i: usize = 0;
+    while (i < 10) {
+        i += 1;
+        if (i % 2 == 0)
+            continue;
+        std.debug.print("foo {d}\n", .{i});
+    }
+}
diff --git a/glfw-vulkan/scratch/goto.zig b/glfw-vulkan/scratch/goto.zig
new file mode 100644
index 0000000..ff02f01
--- /dev/null
+++ b/glfw-vulkan/scratch/goto.zig
@@ -0,0 +1,8 @@
+const std = @import("std");
+
+pub fn main() void {
+    acquire: while (true) {
+        continue :acquire;
+        break :acquire;
+    }
+}
diff --git a/glfw-vulkan/scratch/switch.zig b/glfw-vulkan/scratch/switch.zig
new file mode 100644
index 0000000..0223592
--- /dev/null
+++ b/glfw-vulkan/scratch/switch.zig
@@ -0,0 +1,42 @@
+const std = @import("std");
+
+const Data = enum { foo, bar };
+
+pub fn optional_enum_error_union() !?Data {
+    const state = struct {
+        var flag: u2 = 0;
+    };
+    defer state.flag +%= 1;
+
+    return switch (state.flag) {
+        0 => null,
+        1 => .foo,
+        2 => .bar,
+        3 => error.Fizz,
+    };
+}
+
+pub fn main() !void {
+    for (0..4) |_| {
+        const r1 = if (optional_enum_error_union()) |opt|
+            if (opt) |val|
+                switch (val) {
+                    .foo => "FOO",
+                    .bar => "BAR",
+                }
+            else
+                "NULL"
+        else |err| switch (err) {
+            error.Fizz => "FIZZ",
+            else => return err,
+        };
+
+        const r2 = switch (optional_enum_error_union()) {
+            .foo => "FOO",
+            .bar => "BAR",
+            null => "NULL",
+            error.Fizz => "FIZZ",
+            anyerror => |err| return err,
+        };
+    }
+}
diff --git a/glfw-vulkan/src/linalg.zig b/glfw-vulkan/src/linalg.zig
new file mode 100644
index 0000000..8bf1f5e
--- /dev/null
+++ b/glfw-vulkan/src/linalg.zig
@@ -0,0 +1,99 @@
+const std = @import("std");
+
+// pub fn eye(D: comptime_int, T: type) [D][D]T {
+//     var out: [D][D]T = undefined;
+//     @memset(out, 0);
+//     for (0..D) |d| out[d] = 1;
+//     return out;
+// }
+
+// pub fn eye(D: comptime_int, T: type) [D][D]T {
+//     var out = std.mem.zeroes([D][D]T);
+//     for (0..D) |d| out[d][d] = 1;
+//     return out;
+// }
+
+// pub fn _matmul_result(A: type, B: type) type {
+//     const a = @typeInfo(A);
+//     // const s = a.Pointer.size;
+//     // a.Pointer.size.
+//     const b = @typeInfo(B);
+// }
+// pub fn matmul(A: anytype, B: anytype)
+
+/// r := ab
+pub fn matmul(r: anytype, a: anytype, b: anytype) void {
+    const R = @typeInfo(@TypeOf(r));
+    const A = @typeInfo(@TypeOf(a));
+    const B = @typeInfo(@TypeOf(b));
+
+    // B.Pointer.child
+
+    switch (B) {
+        .Array => {
+            // handle static columns
+            switch (@typeInfo(B.Array.child)) {
+                .Array => {
+                    // handle static rows
+                },
+                .Pointer => {
+                    // handle dynamic rows
+                },
+                else => @compileError("."),
+            }
+        },
+        .Pointer => {
+            switch (@typeInfo(B.Pointer.size)) {
+                .Slice => {
+                    // handle dynamic columns
+                },
+                else => @compileError("."),
+            }
+        },
+        else => @compileError("."),
+    }
+
+    // switch(R) {
+    //     .Array {
+    //         R.Array.sentinel
+    //         // R.Array.len
+    //     },
+    //     .Pointer {
+    //
+    //     },
+    // }
+}
+
+test "matmul" {
+    const a: [3][4]f32 = undefined;
+    const b: [2][3]f32 = undefined;
+
+    var r: [2][4]f32 = undefined;
+    matmul(r, a, b);
+}
+
+test {
+    const alloc = std.testing.allocator;
+    var arr: std.MultiArrayList(std.meta.Tuple(&.{ usize, usize, usize })) = undefined;
+    // try arr.append(alloc, .{ 1, 2, 3 });
+    // try arr.append(alloc, .{ 3, 4, 5 });
+    // try arr.append(alloc, .{ 6, 7, 8 });
+
+    // std.debug.print(comptime fmt: []const u8, args: anytype)
+
+    // [1][4]f32;
+    //
+    // [4][4]f32;
+    //
+    // [][4]f32;
+    //
+    // [4][1]f32;
+
+    // const Vec3f = [3]f32;
+    //
+    // const vv: Vec3f = .{ 1, 0, 0 };
+    // try std.testing.expect(std.mem.eql(f32, &vv, &.{ 1, 0, 0 }));
+    //
+    // const mm = eye(3, f32);
+    // std.debug.print("mm: {any}\n", .{mm});
+}