Actually no, because on the release CD of Common Language Runtime, and the alphas and betas that preceded it, Microsoft collaborated with several companies and universities to have various languages available at lunch date.
Many of which did have a REPL.
Also the dynamic language runtime originally designed for Iron languages, Python and Ruby, precedes F#.
Many of which did have a REPL.
Also the dynamic language runtime originally designed for Iron languages, Python and Ruby, precedes F#.