The same applies to regular jobs. Most job ads have a bullet list of requirements. There is some flexibility but when I was interested in a Ruby job as a C# dev

The same applies to regular jobs. Most job ads have a bullet list of requirements. There is some flexibility but when I was interested in a Ruby job as a C# developer I had a real hard time and didn’t get any offers although I got close. Same for Haskell but there was only one company hiring for that ever in my city. And that is not taking into account the pay hit. Which is a luxury for the unmortgaged/kidless or both.