Well, presumably they're more interested in efficiently implementing their algorithms than in using other MSR technologies for their own sake, but you've got a

Well, presumably they're more interested in efficiently implementing their algorithms than in using other MSR technologies for their own sake, but you've got a point. See http://fsharp.org/testimonials/ http://fsharp.org/testimonials/ for lots of other companies using F#. "Machine learning" only is only mentioned a couple of times, but it sounds like plenty of other companies are doing related work with F# (e.g. Kaggle mentions using it for "data analysis"). (disclosure: I'm doing some contract work with the F# team)