If you want to build a long computer science career as a software developer, you need to pay attention to those programming languages and other skills that will endure for years, if not decades. After all, it’s hard to earn a living off a language that nobody uses anymore. But which languages are in danger of fading away?

To answer that question, we drew on a number of data sources, including RedMonk and the TIOBE Index (which regularly track the popularity of various programming languages). We also turned to Burning Glass, which analyzes millions of blog postings from around the country, to see which software engineering languages face slackening demand over the next 10 years. 

Based on that analysis, we concluded that the following five languages (despite their fans) face significant headwinds in the years ahead. Keep that in mind if you decide to devote time to learning them. 

Perl

According to RedMonk, which ranks programming languages according to data from GitHub and Stack Overflow, Perl has plunged from 11th place in 2012 to 18th place today. That is… not good. Even worse, Burning Glass predicts that demand for Perl-related jobs will tumble 22.1 percent over the next 10 years. 

As readers have pointed out in the past, there’s still a robust developer community around Perl, with updates rolling out on an annual basis. But when we look at job demand, along with code contributed to GitHub, it seems that Perl is seriously on the decline.  

Objective-C

Over the past 12 months, Objective-C has plunged eight ranks on the TIOBE Index—the steepest annual drop of any language in the top 20 (it now sits in 18th place). That’s exactly what Apple, which launched Objective-C 36 years ago as the language for building apps in its ecosystem, really wants; for the past six years, it’s done everything in its power to convince developers to switch to Swift, its new-and-improved programming language.   

Despite that pressure, Objective-C has managed to cling to relatively top positions on the various programming-language rankings, largely because of three-plus decades of legacy code. At some point, though, Objective-C will fade away: Burning Glass predicts that jobs featuring the language will tumble 34.5 percent over the next 10 years. 

C

As a language older than many of the developers who work with it, C occupies a vaunted place within the computer programming world. It’s found its way into a mind-boggling number of applications, from embedded systems to supercomputers. However, Burning Glass suggests that jobs requesting C will dip 14.2 percent over the next 10 years, suggesting that developers are turning to other languages in order to efficiently tackle the building and maintenance of those applications.

Haskell

Although Haskell has its die-hard fans, especially longtime developers who appreciate some of its features (including type classes), the language hasn’t done well on RedMonk’s long-term language rankings, suggesting that there’s little developer chatter around it.

If Haskell faces declining use after three solid decades, at least its fans can comfort themselves by recalling the language’s impact on many of tech’s biggest sites and companies, including Facebook and GitHub.

Ruby

Signs of Ruby’s decline have been present for years. It’s slowly fallen on TIOBE’s programming-language rankings, and last year’s analysis of Dice job-posting data showed a strong dip in the number of companies that wanted technologists skilled in the language. But if you want a true warning sign that Ruby is on the way out, look no further than Burning Glass, which predicts that Ruby jobs will tumble 8.1 percent over the next decade.