Programmers sometimes need to make presentations about projects that they work on, their favourite library or algorithms, or about a shiny new programming language. Slides for such technically-oriented presentations will probably need to contain specific content, such as code snippets with syntax highlighting, complex diagrams, step-by-step animations, math symbols and equations, etc. Here are some examples of slides that I have created which demonstrate what kind of presentations I’m talking about:

What software would you use to create slides for such a technical presentation? It may sound like a simple task that should be handled by any decent tool for creating slides. Yet from my experience, the available solutions (that I know of) are somewhat lacking for this use-case, in several regards.

In this post, I’ll describe what properties I would like to have in a “perfect” tool for creating technically-focused slides and what things I like or dislike about the current available solutions.

In the next post, I’ll try to make an argument for taking a different approach to creating slides, by creating slides programmatically using the Elsie framework.

Please note that this whole post is focused on presentations and slides with technical/computer science content that are exportable to PDF. It might not apply to presentations/slides in general. Also, I am quite a perfectionist when it comes to creating slides.

## Requirements

Here is a list of properties that I’d like to have in a (hypothetical) ideal slide-making tool designed for technical presentations.

• Syntax highlighting Pretty syntax highlighting with support for common programming and configuration languages is an absolute must. I use code snippets in my presentations very often, so I want them to look good, and I also want to experiment with them interactively. Capturing screenshots from an IDE or copying highlighted snippets manually from e.g. carbon is something that I’d really like to avoid.
• Fragments and animations It should support revealing selected contents of a slide gradually and changing its properties (e.g. size/color/position of a piece of text or an image) in individual steps (sometimes called fragments). This should be integrated with code snippets, by allowing the user to e.g. reveal code line by line or to highlight a single line at a time.

It should also allow the user to easily create step-by-step animations by translating/scaling/rotating shapes, text or images, so that this doesn’t have to be performed manually in e.g. Inkscape. As an example, I want to be able to animate e.g. several moves of a chess game, or a packet traveling through a set of connected network devices.

What I don’t really need so much are continuous animations (e.g. GIF or a video), since I want the slides to be exportable to PDF.

• Level of control I want the tool to support both high-level and low-level control of slide creation. More specifically:
• Simple things should be simple… It shouldn’t be too difficult to just slap a piece of text on a slide and call it a day. In most cases, I don’t care about specifying the exact location of some item on a slide, I just want it to be placed and aligned reasonably. I especially don’t want to be forced to align things manually (using the mouse) over and over again.

The tool should thus have a layout model which places and aligns content on a slide automatically, and it should also have the most common slide items built in.

• …and complex things should be possible1 On the other hand, sometimes I do want to place items exactly 30 pixels from the left border, overlay several items on top of each other or create an arrow that will point from the center of an image to the end of the third line of a specific text box.

The tool should thus offer low-level, pixel-perfect control of everything that resides on a slide and let the user build complex visuals when the situation requires it.

• Math symbols and equations I don’t need to render equations or math symbols in presentations that often, but it’s certainly a nice feature to have, especially if your slides are math-heavy.
• Source control The slides should be easily versionable using e.g. git. This allows the user to go back to previous versions of the slides, make modifications without the fear of losing data and to rebuild the slide deck from its source code at any time.
• Export to PDF PDF is (probably?) the best format for distributing presentations. This feature is supported quite well by most tools, so it shouldn’t be a problem.

The tool should also be free to use (or even better, it should be open-source).

Is it too much to ask? Maybe. In any case, I wasn’t aware of any existing tool that would fully satisfy these properties. Now I’ll describe some tools that I have been using so far and what I perceive as their strengths and weaknesses.

## Existing tools

There is obviously a myriad of tools for creating slides and presentations, but I’m mainly interested in those that can be used for creating technical presentations that I have described above. I’ll enumerate solutions that I have personally used for creating slides for such presentations.

Note that the list of strengths and weakness is quite opinionated and biased :) It is also possible that I have missed some popular alternatives, so if you know of any other software tools for creating (technically-oriented) slides, please let me know on Reddit!

### PowerPoint-like tools

I’m putting tools such as PowerPoint, Google Slides, Impress, Prezi,… into a single category, because they all represent the (probably most common) slide creation archetype, which uses a WYSIWYG editor for creating slides. These tools are fine if you need to make a bunch of very simple slides quickly, but using them gets pretty annoying if you need anything more complex.

My biggest gripe with these tools is that using them is a very manual and laborous process, because you mostly need to place and align items on a slide manually using the mouse. Sure, you get the occasional “grid-snapping” functionality to help you, but that is a small band-aid and sometimes it can become pretty annoying if it doesn’t snap in the way you want.

Furthermore, if you want to experiment with some property/detail that occurs on multiple slides (for example: change the font or size of all text), you often need to go through all the slides to modify them one by one, which is exhausting.

• Syntax highlighting Support for code snippets is pretty weak. You basically have to resort to importing code as an image which has been highlighted by another tool (an IDE, carbon.sh, pygments, etc.). It’s not that bad if you do it once. But after you are editing the same code snippet on a slide for the twentieth time, or you decide that you want to change the highlight theme of all the code snippets in your presentation, it quickly becomes annoying.
• Fragments and animations You can reveal parts of your slide, for example items of a list or parts of a paragraph, but the options are somewhat discrete and limited. I haven’t found a simple way in PowerPoint to e.g. show some text, then hide it, then show some other text at the same time as an image and then show the original text again. It may sound like a convoluted example, but I want to display similar visuals in my slides fairly often, and these kinds of tools don’t allow me to express them easily.

PowerPoint can actually create pretty nice continous/moving animations, but that is not very useful when you want to export to PDF.

• High-level control PowerPoint has a lot of features to create lists, tables, charts, and it also has advanced formatting, editing and spellchecking features, so you get a lot of things built-in. Yet placement and alignment is not automated as well as I would like.
• Low-level control While you can place things pretty much where you want, you need to do it manually ba hand, and creating complex animated diagrams is very time-consuming.
• Math symbols and equations PowerPoint has support for rendering equations, but it’s a bit cumbersome and not really on the level of TeX.
• Source control Not really possible using git. These tools support various forms of history, but it’s very crude compared to proper source control.

### Beamer

(La)TeX is a typesetting system popular within the scientific community, which uses a declarative language to typeset and render documents. There is a LaTeX template named Beamer, which is designed for creating presentations2.

• Syntax highlighting Code highlighting in Beamer is pretty good, thanks to the minted package. It supports theming, line numbers and overall it is pretty solid.
• Fragments and animations Beamer has support for basic fragments and revealing, but it’s not so easy to support more advanced use-cases. You can create complex animations using the very powerful TikZ package, but it has (at least in my opinion) a pretty steep learning curve, and it can get somewhat verbose because of it declarative nature. For me, this is probably the biggest annoyance of Beamer (followed by its very unhelpful error messages :) ).
• High-level control LaTeX has pretty good support for lists, tables, etc. While a declarative solution will probably never match the simplicity of WYSIWYG editing for creating really simple items, I don’t feel that Beamer is too verbose even for basic slides.
• Low-level control LaTeX allows you to place things with a low of control, so in this regard it gives you a lot of flexibility. Complex visuals are possible to do with TikZ, but again, it often feels a bit too complicated to me.
• Math symbols and equations LaTeX obviously shines here, since it was designed exactly for this use-case. You probably won’t find a better tool if you need to render a lot of equations, math symbols, proofs, etc.
• Source control It is easy to version LaTeX, since it’s just text-based source code.

LaTeX is notable for producing fine-looking text and has very good typesetting. If you can make sense of LaTeX errors, you don’t mind its syntax and you can speak TikZ, I think that Beamer is actually a pretty good choice.

### Reveal.js

This is a great tool for making HTML presentations. Its presentations look nice, they can work in both interactive (in a browser) or presentation (exported to PDF) modes and its familiar HTML/CSS syntax is more approachable than (sometimes quite ugly) LaTeX code. However, it shares some disadvantages of LaTeX/Beamer, which stems from the fact that it is also declarative.

• Syntax highlighting Code highlighting is quite good. It also supports theming and line numbers, and it even has support for highlighting parts of the source code gradually out of the box.
• Fragments and animations Again, this is a point of contention for me. The tool supports basic fragments and also some advanced scenarios, but you cannot really express complex animations or build complex diagrams easily using HTML. You can actually use JavaScript to create these things, but it’s not integrated, the library does not offer you API to make it easier, so it’s pretty cumbersome.
• High-level control Reveal.js uses HTML and CSS, so it allows you to build a lot of UI elements very simply, and you can use a myriad of layout models (e.g. flexbox) to lay them out on the slide.
• Low-level control Using CSS, you can achieve pixel-perfect placement. Yet creating complex visuals (without the use of JavaScript) is only possible to a certain extent.
• Math symbols and equations The tool supports MathJax , which is basically LaTeX rendered in the browser. Support for rendering math is thus quite good.
• Source control Again, the source is just text, so it is easy to put it under source control. Reveal.js presentations are distributed as directories with quite a few files, but it’s not really a big problem for git.

### Markdown-based tools

There are also quite a few tools that can render Markdown into a set of slides (for example Marp). Markdown is a great tool for creating nicely-looking content quickly, and if it matches your use-case, you should definitely use it. However, I cannot imagine creating complex visuals, diagrams or animations using Markdown syntax, since it is highly declarative and also quite limited in what it can do (which is actually its goal and a benefit in many situations).

Therefore, I consider Markdown-based solutions to have very similar properties to reveal.js, just with a different markup language (HTML vs Markdown).

## Conclusion

In general, these tools can be divided into two categories - tools with WYSIWYG editing (such as PowerPoint) and tools with declarative source code (such as Beamer or reveal.js).

• WYSIWYG editing tools require a lot of manual labor to create beautiful slides, which usually leads to one of two things - you either spend way too much time making your slides look pretty, or you gloss over it to save time and then end up with mediocre slides.

• Declarative tools are quite useful for creating technical slides and can get you quickly to 90% of the desired result. As you might have noticed from the list above, I basically like the existing declarative tools, and I have used them many times for creating presentations. However, too often achieving the final 10% of the desired result gets exponentially harder to achieve using declarative tools.

So, this is the end of my rant :) In the next post, I’ll show you that slides can also be created differently, by taking the useful features of existing declarative tools and combining them with the power of an imperative programming language.

1. Quoting Alan Kay and also Larry Wall

2. It is often used for technical presentations especially in academic environments.