Designing an interface to create interfaces

January 2 2010

I’ve been reading Coders at Work recently and this blog post is spawned from a point made by Simon Peyton Jones in the book — Page 252, Paragraph 3 — about creating usable programming languages.

When the field of HCI was established in the early 1980s, learnability was the research focus. By the late 1980s we had a handle on how to design for the novice user, demonstrating that even the best commercially available personal computer was much harder to learn than claimed by it’s manufacturer.

We created computers because our ability to think using rigorous logic is limited in terms of speed, capacity and accuracy. Given these limitations, shouldn’t any interfaces we create play to our strengths without demanding too much from our weaknesses?

Programming languages go through rapid development to fit formal (hardware) specifications and have meant that usability best practices have fallen by the way-side. However, usability is holistic and something that has to be intentionally designed in from the beginning rather than slapped on at the end.

Usability studies in this area are lacking, but there are some that have managed to have an effect on the final product. More recently though, full on task forces have been springing up and providing good information on designing the interface that creates the interface.

Testing products with a steep learning curve

As stated by Jakob Nielson in his Iterative User Interface Design paper:

For some user interfaces, full expertise may take several years to acquire, and even for simpler interfaces, one would normally need to train users for several weeks or months before their performance plateaued out at the expert level

Sadly, by the time you’ve learnt how to use the product effectively, you’re too biased to comment on it’s usability fairly. This is just one of the fundamental limits on usability testing of complicated products. Despite this, there is still knowledge to be gained from testing programming languages at a novice or intermediate level.

A simple programming test could be held, with people who have the same amount of training — university students? — in different languages and then measure factors ranging from the number of errors along the way, to overall performance. A simple task may involve scraping data from a set of web pages such as and organising them into a searchable data structure. The user could attempt to use any programming language but a time-limit would need to be set to keep the test fair.

Libraries vs. Languages

Being a programmer, I tend to look for solutions by dissecting the problem into smaller chunks and in many cases that makes me lean towards libraries. It’s likely that any seasoned developer would do the same, opting for the best tools for the job rather than any one single language. Does this fulfil the efficient use category of usability? No.

Most of these libraries are built by software developers to facilitate their work, increasing the need for usability in this particular area. If something is too time-consuming, a developer will automate it. However it does then raise the question of whether the flaws lie in the language, where the expert knowledge is needed to understand how to automate a given task in the first place.

Can we have a yardstick?

There is ample evidence to support the notion that experts behave differently from novices, but that should never mean we pick one of these two groups and design specifically for them. Program designers should understand the context of use, set appropriate goals, and measure that we are achieving those goals. The myriad of different programming paradigms mean that we can’t effectively compare the usability of different languages, but that shouldn’t hinder the process of increasing usability for the lowest common denominator.

The lack of cross-over between Funtional, Procedural or even Event-based programming languages makes formalising a test harness extremely difficult. Attempting to test all of the different kinds of programming languages may produce a clear winner in terms of usability, but are likely to fail large proportions of the development community.

Disclaimer: I would never pretend to be an expert in this area, so I’m sure there is a lot of good material that I’m not aware of yet. Please let me know if you have any further useful information.