Higher Logics

In playing around with Razor Pages, I was irritated again that Microsoft couldn't just standardize a set of interfaces for their methods so that they wouldn't need so much magic. So I just quickly hacked up RazorInterfaces , available also on nuget.org . It's probably most useful to people just learning Razor Pages, since it requires you to correctly implement the common HTTP methods you'll need to get things running: public class CustomerPage : PageModel , IPageGet , IPagePostAsync<Customer> { public IActionResult OnGet() { return Page(); } public async Task<IActionResult> OnPostAsync(Customer customer) { await DataLayer.Update(customer); return Page(); } } There are interfaces for all of the standard HTTP methods: GET, POST, PUT, DELETE, HEAD, OPTIONS. The interface names conform to the following format: IPage[HTTP method] and IPage[HTTP method]Async for the async variant, and there a...

After a long hiatus, I'm slowly starting back on blogging and some personal projects. To get me back in the swing of things, here's a short post on running ASP.NET core on Google Cloud, since this seems poorly documented online. The default project created by the Google Cloud tools includes Microsoft.AspNetCore.All which is a huge dependency. If you want something more minimal: uninstall-package Microsoft.AspNetCore.All install-package Microsoft.AspNetCore install-package Microsoft.AspNetCore.Mvc.Core install-package Microsoft.AspNetCore.Mvc This creates a runnable project using the standard Google Cloud Web API project template, although it still isn't ideal as it includes the Razor pages dependencies.

A thread on reddit pointed to Canada's consultation on what sort of legislative framework they should create to facilitate investigations in the digital world. Many of the questions are leading and borderline deceptive in their phrasing, but if we're being charitable, this is a good opportunity to inform policy makers. To that end, these are my responses: How can the Government address challenges to law enforcement and national security investigations posed by the evolving technological landscape in a manner that is consistent with Canadian values, including respect for privacy, provision of security and the protection of economic interests? Evidence-based policy suggest you first demonstrate the actual need for such respective legislative changes, and further, that the proposed changes actually solve the problems they are intended to solve. Impartial third-party studies should be required for any proposed measures. As a computer scientist with some expertise in computer...

There are plenty of tutorials online for creating tabbed panels in HTML documents, some using JavaScript, some using pure CSS tricks. Most of the approaches seem to assume that a list of some type is the appropriate element to use for a tabbed interface, but I'd argue that lists are not semantically descriptive of tabbed interfaces. They either include the main tab content along with the tab name, like so: <ul class="tabs"> <li class="tab-active"><a href="">Active</a> Active tab content goes here</li> <li><a href="">Second</a> Inactive second tab content goes here</li> <li><a href="">Third</a></li> </ul> Or the tab content has no semantic relationship with the tabs that control their display, like: <ul class="tabs"> <li class="tab-active"><a href="#first">Active</a></li> ...

In any system with mutable entities saved in an object store, it's inevitable that you'll want to audit the changes made to a particular entity. Explicitly versioning your entities solves this problem, and it's often pretty useful to end users of a sophisticated application, say for undo purposes. However, it's not always so clear how to transform a mutable entity into an versioned entity. There are also a number of complications to versioning mutable objects: Handling parent-child relations such that a child change does not propagate to every parent Supporting efficient queries on history Supporting efficient queries for the newest version Space complexity of data representation Concurrent changes Some of the above properties also have a natural tension, ie. supporting efficient queries often require storing more data so their space complexity is worse. I'm going to provide an overview here of a very simple schema for versioned entities with the following...

I just wanted to jot down some thoughts on compiling eval/apply curried application using an efficient register-based calling convention. This translation is actually quite simple once you get the trick. Leroy's Zinc abstract machine showed the way: evaluate arguments right-to-left instead of the typical left-to-right. The ZAM wrote these arguments to a stack, but in our case we want them to go to the register file first. So we evaluate arguments right-to-left and write them into registers left-to-right, ie. argN goes in reg0, argN-1 goes to reg 1, ... arg0 goes to regN. At some threshold, we'll run out of registers. If your program is in direct-style with a stack, this threshold is often defined by the callee-save registers of the native calling convention. If your program is in CPS form, then you can use the entire register file. Once you run out of registers, you have to spill the remaining arguments to the stack. However, the stack is simply a register pointing to some...

Algebra.NET is a simple library designed to facilitate easy expression and manipulation of algebraic functions. For instance, here's a simple function: Function<Func<double, double>> a = Algebra.Function(x => 2 * x + 1); We can compile such a function to efficient IL: Func<double, double> func = a.Compile("times2plus1"); Or we can apply some algebraic identities to rewrite it: Identity associative = Algebra.Identity(x => x + 1 == 1 + x); Identity mulEqAdd = Algebra.Identity(x => 2 * x == x + x); Console.WriteLine(a); Console.WriteLine(a.Rewrite(1, associative, mulEqAdd)); // Prints: // ((2 * x) + 1) // (1 + (x + x)) Rewrites can sometimes loop forever (consider "x + y == y + x"), so the Rewrite method takes a number indicating the maximum number of iterations to perform all the rewrites. All the usual arithmetic operations are available, including an extension method for exponentiation: var f = Algebra.Function(x => x.Po...