Consolidate algorithm examples into one dir

examples/algorithms/fibonacci-platform/Package-Config.roc

@@ -0,0 +1,9 @@
+platform "fibonacci"
+    requires {} { main : I64 -> I64 }
+    exposes []
+    packages {}
+    imports []
+    provides [ mainForHost ]
+
+mainForHost : I64 -> I64
+mainForHost = \a -> main a

examples/algorithms/fibonacci-platform/host.zig

@@ -0,0 +1,97 @@
+const std = @import("std");
+const testing = std.testing;
+const expectEqual = testing.expectEqual;
+const expect = testing.expect;
+
+comptime {
+    // This is a workaround for https://github.com/ziglang/zig/issues/8218
+    // which is only necessary on macOS.
+    //
+    // Once that issue is fixed, we can undo the changes in
+    // 177cf12e0555147faa4d436e52fc15175c2c4ff0 and go back to passing
+    // -fcompiler-rt in link.rs instead of doing this. Note that this
+    // workaround is present in many host.zig files, so make sure to undo
+    // it everywhere!
+    if (std.builtin.os.tag == .macos) {
+        _ = @import("compiler_rt");
+    }
+}
+
+const mem = std.mem;
+const Allocator = mem.Allocator;
+
+// NOTE the LLVM backend expects this signature
+// extern fn roc__mainForHost_1_exposed(i64, *i64) void;
+extern fn roc__mainForHost_1_exposed(i64) i64;
+
+const Align = extern struct { a: usize, b: usize };
+extern fn malloc(size: usize) callconv(.C) ?*align(@alignOf(Align)) c_void;
+extern fn realloc(c_ptr: [*]align(@alignOf(Align)) u8, size: usize) callconv(.C) ?*c_void;
+extern fn free(c_ptr: [*]align(@alignOf(Align)) u8) callconv(.C) void;
+
+const DEBUG: bool = false;
+
+export fn roc_alloc(size: usize, alignment: u32) callconv(.C) ?*c_void {
+    if (DEBUG) {
+        var ptr = malloc(size);
+        const stdout = std.io.getStdOut().writer();
+        stdout.print("alloc:   {d} (alignment {d}, size {d})\n", .{ ptr, alignment, size }) catch unreachable;
+        return ptr;
+    } else {
+        return malloc(size);
+    }
+}
+
+export fn roc_realloc(c_ptr: *c_void, new_size: usize, old_size: usize, alignment: u32) callconv(.C) ?*c_void {
+    if (DEBUG) {
+        const stdout = std.io.getStdOut().writer();
+        stdout.print("realloc: {d} (alignment {d}, old_size {d})\n", .{ c_ptr, alignment, old_size }) catch unreachable;
+    }
+
+    return realloc(@alignCast(@alignOf(Align), @ptrCast([*]u8, c_ptr)), new_size);
+}
+
+export fn roc_dealloc(c_ptr: *c_void, alignment: u32) callconv(.C) void {
+    if (DEBUG) {
+        const stdout = std.io.getStdOut().writer();
+        stdout.print("dealloc: {d} (alignment {d})\n", .{ c_ptr, alignment }) catch unreachable;
+    }
+
+    free(@alignCast(@alignOf(Align), @ptrCast([*]u8, c_ptr)));
+}
+
+export fn roc_panic(c_ptr: *c_void, tag_id: u32) callconv(.C) void {
+    _ = tag_id;
+
+    const stderr = std.io.getStdErr().writer();
+    const msg = @ptrCast([*:0]const u8, c_ptr);
+    stderr.print("Application crashed with message\n\n    {s}\n\nShutting down\n", .{msg}) catch unreachable;
+    std.process.exit(0);
+}
+
+pub export fn main() u8 {
+    const stdout = std.io.getStdOut().writer();
+    const stderr = std.io.getStdErr().writer();
+
+    // start time
+    var ts1: std.os.timespec = undefined;
+    std.os.clock_gettime(std.os.CLOCK_REALTIME, &ts1) catch unreachable;
+
+    const result = roc__mainForHost_1_exposed(10);
+
+    // end time
+    var ts2: std.os.timespec = undefined;
+    std.os.clock_gettime(std.os.CLOCK_REALTIME, &ts2) catch unreachable;
+
+    stdout.print("{d}\n", .{result}) catch unreachable;
+
+    const delta = to_seconds(ts2) - to_seconds(ts1);
+
+    stderr.print("runtime: {d:.3}ms\n", .{delta * 1000}) catch unreachable;
+
+    return 0;
+}
+
+fn to_seconds(tms: std.os.timespec) f64 {
+    return @intToFloat(f64, tms.tv_sec) + (@intToFloat(f64, tms.tv_nsec) / 1_000_000_000.0);
+}