Test-driven developers should feel right at home in functional languages like F#: small functions that give deterministically repeatable results lend themselves perfectly to unit tests. There are also capabilities in the F# language that facilitate writing tests. Take, for example, Object Expressions. You can very easily write fakes for functions that take as their input … Read more
You can do it like this: let p = new Person (Name = “John”, BirthDate = DateTime.Now)
In F# (|>) is important because of the left-to-right typechecking. For example: List.map (fun x -> x.Value) xs generally won’t typecheck, because even if the type of xs is known, the type of the argument x to the lambda isn’t known at the time the typechecker sees it, so it doesn’t know how to resolve … Read more
The French and British descendants of the original ML made different choices and their choices have been inherited through the decades to the modern variants. So this is just legacy but it does affect idioms in these languages. Functions are not recursive by default in the French CAML family of languages (including OCaml). This choice … Read more
Daniel already explained how to define a C#-friendly version of the F# function that you wrote, so I’ll add some higher-level comments. First of all, you should read the F# Component Design Guidelines (referenced already by gradbot). This is a document that explains how to design F# and .NET libraries using F# and it should … Read more
The problem is that the min3 function is compiled as a generic function that uses generic comparison (I thought this uses just IComparable, but it is actually more complicated – it would use structural comparison for F# types and it’s fairly complex logic). > let min3(a, b, c) = min a (min b c);; val … Read more
You can use Enumerable.Range(0, 10);. Example: var seq = Enumerable.Range(0, 10); MSDN page here.
This question has been answered for some time now, but I was quite surprised that most of the answers say what OCaml features are missing in F# – this is definitely good to know if you want to port existing OCaml programs to F# (which is probably the motivation of most of the referenced articles). … Read more
Haskell is a “pure” functional language, where as F# has aspects of both imperative/OO and functional languages. Haskell also has lazy evaluation, which is fairly rare amongst functional languages. What do these things mean? A pure functional language, means there are no side effects (or changes in shared state, when a function is called) which … Read more
In addition to what Lee said, you can define reduce in terms of fold, but not (easily) the other way round: let reduce f list = match list with | head::tail -> List.fold f head tail | [] -> failwith “The list was empty!” The fact that fold takes an explicit initial value for the … Read more