T-Dose 2014, Zimbu Designing a Programming Language From Experience, Bram Moolenaar

Bram Moolenaar discusses designing the Zimbu programming language based on practical experience and the requirements of building a text editor.

CityTV.nl t-dose.org zimbu.org moolenaar.net Playlist: youtube.com/playlist?list=PLBZBIkixHEidJ05uKM6orHYps0A0uNQ94 26 10 2014 T-Dose 2014, Zimbu Designing a Programming Language From Experience, Bram Moolenaar Programmers have been creating code for a long time now. We have learned what works well and what leads to doom. With this knowledge we can design a programming language that helps programmers do their work productively. Choices can be made from experience, instead of using some academic theory or the hot fashion of the year. Even though many programming languages already exist, it's hard to make a choice for something like creating a text editor. Adding up all the requirements, there really is not one language that fulfills them all. So let's make one! This talk takes a list of important observations from the daily work of programmers and discusses what that means for the choices made in designing a programming language. Many alternative solutions can be found in existing languages, some old and some new. It is mainly a matter of evaluating these alternatives and picking the right solution using our collective experience. But in some cases we just can't find the right solution and have to invent something new. For example, one important choice is how to structure code, how to keep code that belongs together in once place. An observation is that we will always want to add new features on top of existing code. There must be a good way to extend what is already there, without rewriting it for every new feature. The mechanism of inheritance in object-oriented programming solves this partly. We have learned that multiple inheritance is too complex. But single inheritance doesn't cover what we need. The solution lies in mixins: blocks of functionality that can be used and re-used. This gives the programmer the choice to use inheritance where that makes sense, and mixin code blocks where that works well. Another observation, which is rather obvious: Code is read ten times more often than it is written. Being able to write quickly is not all that important, being able to read and understand it easily is essential. Many languages have made the mistake to make code easy to write but hard to read. Others require that variable types are specified in great detail, making it difficult to see what the code is actually doing. It is possible to find a balance between the two, there are a few new languages that have solutions in this area. An example of where no existing language offers a good solution is supporting code generation. This is possible, of course, but requires writing a Makefile and/or scripts in some other language, which often end up not being portable and require installing a wild variety of other tools. We can observe this causing serious maintenance problems. The solution comes not from existing programming languages, but from applications: plugins. Compiler plugins, writte