Craft & Artfulness

https://codepen.io/wshager/full/zWBzMV It says "directed acyclic word graph", which I think is the correct term, but I just found out on Wikipedia  that this is indeed a trie. The difference is illustrated quite precisely, but I think it's really the same thing. I didn't use an existing algorithm, but I just made this up myself. I didn't study computer science (and I'm mostly glad I didn't). If you did, let me know if it's any good.

Writing parsers is not for humans. Humans define grammars, and feed those to parsers. However, I was determined to try my hand at making a parser for XQuery in XQuery as a human, because I saw that the language is actually quite consistent. The same is true for XML and S-expressions, for example, and for those languages there already exist hand-built parsers (for example in in JavaScript, see https://github.com/isaacs/sax-js and https://github.com/fwg/s-expression respectively). After all, how hard can it be? Well pretty damn hard, as I've worked on it on and off for two years. Yet only recently I came up with three basic utility functions that help to understand how a parser actually works. These functions are variations of the widely known reduce  (or fold ) function. Looking ahead What you often need to do when parsing a string of text – character by character – is to look at what the next character is. For example, a colon has several different meanings in XQu...

Programmeren is zowel een wetenschap als een gereedschap. De "man van de praktijk" loopt gaandeweg tegen problemen aan die formeel allang verkend zijn. Deze zaken zijn veelal uitgewerkt in ingewikkelde wetenschappelijke publicaties. Dat niet iedereen die leest is begrijpelijk, maar veel kennis is ook geïmplementeerd in functionele talen, als Haskell, Scala en recente LISP/ML varianten. Om inzicht te krijgen in fundamentele concepten is het verstandig om contact te houden met de ontwikkelingen in dergelijke talen. Ook in Javascript begint deze kennis door te dringen, al is dit geen zuivere functionele taal... Kennis van zuiver functioneel programmeren opdoen kan door zelf een taal te leren of door bronnen te raadplegen op het WWW, zoals diverse blogs en tutorials (er zijn ook veel videos) of hulp te vragen van experts op StackOverflow. Het doel is niet om zo'n taal te gebruiken, maar om concepten te doorgronden die eraan ten grondslag liggen. Dit geldt overigens ook voor...

This is a small series on HTML forms. The previous post was  Forms as state containers Part 3: validation . With form generation we leave the realm of functional form controls. In addition to barebones client logic, we have to focus on the User. Many programmers tend to forget that. However, the devil is in the details. You may just want to add a simple form to capture an email address for a newsletter subscription, or an entire multi-lingual webshop with checkout system, it's all the same, really. No matter the use case, the accessibility, look & feel and ease of use of the app are just as important as the validity of the data. Unfortunately, this is were many applications fail, as we've all experienced at some point. There's not one way to solve the "forms problem", as there's an insurmountable gap between user, designer and programmer. In my opinion, the ultimate goal is: enough flexibility, with the ability for designers to rapidly create working p...

This is a small series on HTML forms. The previous post was Forms as state containers Part 2: managing complex data . A form is a schema Since HTML5 there are a lot more attributes avaiblable on form components for expressing constraints. This means forms can nowadays be used as a basic schema for validating data. However, HTML5 form components are a motley crew, so we need some guiding principle to actually make sense of it all. JSON Schema  provides a coherent set of constraints for JSON data. And because JSON is just javascript, JSON Schema should be readily applicable to HTML forms as well. You may not know or like JSON Schema, or you may not want to learn it because it isn't a standard (yet), so in this post I'll try to patch up things by merging JSON Schema into the HTML forms standard. To start it off, some very useful keywords from JSON Schema actually translate directly to HTML5 form constraints. For this purpose I'm considering the version 0.4 draft. ...

This is a short rant that was originally part of my HTML forms write-up , but that I took out, because it became too long. I haven't been writing unobtrusive javascript for at least a decade, and perhaps that was a mistake, but it was also inevitable. In my own defense: it seems HTML is actually quite incoherent... Yup, I just wrote that. I mean, you have tags that denote text levels, similar to those used in text processing software, like paragraph , header , blockquote and (later on) the HTML5 semantic tag set . You also have tags that denote some concrete representational blocks that can be considered part of the document flow, like img  and table , or more generic tags that can be used to manipulate document flow, like div or span . The hyperlink is the VIP of the web, and a different beast altogether. Then there's the  form,  with its controls, which isn't representational at all, but primarily  functional . I think the distinction between representa...

This is a small series on HTML forms. The previous post was Forms as state containers Part 1: forms as a single source of truth JSON? The value of a form can be seen as a key/value map, a plain object in JSON. From this follows that the value of a subform naturally becomes an object in the parent form. In HTML5 subforms can be expressed as a fieldset  element. However, the javascript interface of a fieldset is not a natural fit as a subform, since it only groups elements in the parent form: the elements remain accessible in the parent form. Wrapping the fieldset interface slightly in a thin javascript layer, we can treat fieldsets as a true subform, and we can address its "value" property as an object. In the unlikely event that the form doesn't have access to javascript, we may have have another solution, as we'll see later on. Repeating values obviously fit naturally to javascript arrays. The "value" property of, for example, a multi-select gets (or ...