F# 101

riginally a research language from Microsoft Research, F# has long been a "secret weapon" in the arsenal of .NET programmers for doing statistically and mathematically heavy coding. More recently, however, a growing number of developers have begun to see the inherent advantages implicit in writing functional code, particularly in the areas of concurrency. The buzz has begun to approach interesting levels following on the heels of an announcement last year from the head of the Microsoft Developer Division, S. "Soma" Somasegar, that F# would be "productized" and fully supported by Microsoft as a whole, suddenly removing the stigma and licensing restrictions that surround research projects.

One of the more recent ideas that's sweeping the industry is the notion of "domain-specific languages," (DSLs) whereby a developer builds a language that others (typically either skilled knowledge workers/subject matter experts, or sometimes even other programmers) will use to solve the particular business problems facing them. As Neal Ford describes, two different kinds of DSLs permeate the space: internal DSLs, built on top of an existing language's syntax, and external DSLs, built in some of the same ways as languages such as C# and Visual Basic—with a parser, an abstract syntax tree to store the parsed code, and either an interpreter to run the resulting program, or a code generator to turn it into an executable program.