How to Measure Programming Language Complexity

Here’s a useful metric for programming language complexity: the number of keywords or reserved words in the language. This corresponds roughly to the number of language features and, hence, the size of the language.

1. F# — 69 + 8 from OCaml + 26 future = 103
2. C# — 79 + 23 contextual = 102
3. C++ — 93
4. Swift — 93
5. Kotlin — 30 + 17 soft + 29 modifiers + 2 special = 78
6. PHP — 67
7. Nim — 66
8. JavaScript (or ECMAScript)—64 (or 34 + 7 future = 41)
9. Dart — 56
10. Haskell — 55
11. Rust — 35 + 17 future = 52
12. Java — 50
13. Perl — 40
14. Scala — 40
15. Ruby — 39
16. Julia — 38
17. Objective-C — 37
18. Scheme — 37
19. Python — 33
20. C — 32
21. Go (or Golang )— 25
22. Lua — 21
23. Elixir — 18
24. Smalltalk — 6

Note that for JavaScript, if you’re working with legacy code, you may have to deal with the larger language (64 keywords).

The metric isn’t perfect but it provides a reasonable indicator of complexity. Obviously, C++ and Swift are very large and complex languages. F# has the potential to be the most complex language on the list.

JavaScript is considerably more complex than Java, and ECMAScript is certainly more complex than Python.

Smalltalk. What can I say? Languages don’t get any simpler than this one (except for Forth).