Feel free to point me to other answers if these have already been asked!
I'm just starting F# with the new release this month. I've got some background in both OO and functional languages (Haskell and Scheme, but not OCaml/ML). A couple of questions have arisen so far from reading through the little tutorial thing that comes with the F# CTP.
1) Are mutable variables preferred over monads? If so, are monads entirely shunned in F#?
2) I'm a tad confused by the capitalization being used. In this tutorial code file, sometimes functions start with a lowercase letter, and sometimes uppercase. I know MS tends to like initial caps with functions and methods, but here it seems like there are two ways of doing it. It's not a huge deal to me, as I'm just playing around on my own time, but I am curious what the standard is.
3) I'm pretty confused about this whole combination of OO and functional styles. print_string "string" makes sense, but then here is List.map fn list (unless List is just the namespace, forgive me if so). Then here is str.Length. Anyone care to elucidate when to use what, and which is preferred?
Thanks!
Regarding mutability: F# allows you to be pragmatic. I rarely prefer a state monad to a mutable/ref, but you can do whichever you like. Monads are not shunned, but I think people tend to only use them when they're a clear-cut win (e.g. async programming).
Regarding naming: there is a tension in the fact that 'functions are values' means you might choose to name a let-bound function with a capital letter (because it's a function, and functions begin with capitals) or with a lower-case letter (because it's a let-bound value (that just happens to have an '->' in its type name)). Personally I prefer to always use upper-case names for all functions, but you'll see both styles (especially since the style of the F# library itself has been slowly evolving/standardizing over the past year or two). Underscores seem to be shunned throughout .Net, and the F# library is no longer an exception (there are a few names left that use underscores, but they stand out now like a sore thumb and will probably be changed).
Regarding function style: I am unclear what you are asking. In the case of List.map, 'List' is the name of an F# module, and 'map' is a function in that module. Member functions (e.g. str.Length) have the advantage of being commonly used throughout .Net, and provide a nice intellisense experience in the editor.