Goodness in programming languages, part 1 – syntax and layout

In this series I will comment on what I like in some of the languages I use. I will cover things that I find convenient, things that might lead me to write correct code, things that tend to make my code more readable, and possibly other things that I just like for no clearly-articulated reason. The purpose of this series is to help me think about what features I would put in a language if I created my own.

Posts in this series: Syntax, Deployment, Metaprogramming, Ownership

What aspects of syntax and layout – how the code appears in your text editor – do I like? This is entirely irrelevant to the computer that is running the code, and an implementation detail of the language compiler or interpreter, but is extremely important to me.

  • Python and Scheme’s low-symbol approach. Python and Scheme tend towards the use of English words, rather than symbols to express concepts. This makes code easier to read for someone unfamiliar with the language, and also for me.
  • Python’s unambiguous block structure. Python uses indentation to express block structure (e.g. for variable scope, namespaces and logic structures). Programmers in most languages (notably C-like and Lisp-like ones) tend to use indentation to help humans understand the block structure of their code, but the computer uses different symbols to understand the same thing. This can lead to ambiguity where a human may mis-read the real block structure of some code because the indentation is inconsistent with the symbols. Python avoids the problem by making indentation the syntax understood by the compiler. [Go avoids the same problem by stating that code with inconsistent indenting (as defined by the gofmt program) is invalid.]
  • Scheme’s simplicity. Scheme (like other Lisp dialects) has very simple rules to describe its syntax. This means you need to learn very little before you can understand the structure of Scheme programs, and it is unlikely you will be confused by rare structures.

Of course, there are trade-offs in all these points. Using fewer symbols can make programs verbose (although I find Python feels very concise). The lack of an end-of-block symbol makes short Python snippets look clean, but can make longer sections hard to understand (perhaps better editor support would help with this?). Scheme’s use of brackets for everything means there are a lot of brackets, so working out which does what job can be difficult.

Nevertheless, the goals of reducing the number of symbols with special meaning, allowing humans and computers to use the same ways of understanding code, and being as simple as possible are good goals to have.

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