[the_benno]

F# is an ML-family language, and ML stands for meta-language -- it was designed for language tools and compilers! Andrew Appel's Modern Compiler Implementation in ML is a great resource for code examples that aren't exactly F#, but will look damn close. The book has also been published with C and Java, if you want side-by-side comparisons

[pfdietz]

ML was designed to be the metalanguage for the LCF proof system, used to write proof tactics. It was then recognized to be interesting in its own right as a programming language.

[the_benno]

Oh, thanks for the correction and apologies for the inadvertent misinfo.

Your comment sent me reading the HOPL paper about SML -- I think I (based on folklore knowledge/informal conversations) conflate the original development of ML with subsequent development and standardization around SML. All of this was well before my time so it's quite interesting to read about some of the details.