November’s edition of the TIOBE Index, which ranks programming languages on popularity, contains precious few surprises: yet again, Java, C, C++, C#, and Python occupy the top five ranks. The Index, which is updated once a month, uses data from search engines such as Google, Bing, and Amazon to calculate its rankings. As a result, the Index isn’t a reflection of the languages with the largest install base. Nonetheless, its monthly results can indicate which languages are on the rise, and which are beginning to decline from lack of use. Which brings us to one of TIOBE’s highlights for November: Haskell, a 26-year-old programming language, has continued to grow in popularity, coming within 0.255 percent of breaking into the Index’s top 20 languages. Haskell is a general-purpose programming language with non-strict semantics and strong static typing. Purely functional, its functions have no side effects when interacting with filesystems and other outside-world elements; a separate construct represents those side effects. It also features web frameworks and thousands of open-source libraries and tools, if you want to play around with it a bit. Like some wines, the language is clearly aging well. Companies that rely on Haskell include Facebook (as part of its anti-spam implementation) and various cryptography-centric startups. The language is used in everything from system-tools development to testing advanced programming features to security. Haskell isn’t the only smaller language rising in TIOBE’s rankings. Last month, the researchers behind the Index reported that Go and Groovy had enjoyed significant gains over the past year, the former boosted by its use in the popular container application Go. Swift, which is Apple’s updated language for building iOS and macOS apps, has also climbed rapidly since its introduction in 2014, as has R, which is used in statistical computing.