This looks like a nasty corner-case in the F# language, but I’m not sure if it qualifies as a by-design limitation or a bug in the compiler. If it is by design limitation, then the error message should say that (because currently, it doesn’t make much sense). Anyway, the problem is that the F# compiler … Read more
using Fluent DateTime https://github.com/FluentDateTime/FluentDateTime var dateTime = DateTime.Now.AddBusinessDays(4);
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
type Overloads = Overloads with static member ($) (Overloads, m1: #IMeasurable) = fun (m2: #IMeasurable) -> m1.Measure + m2.Measure static member ($) (Overloads, m1: int) = fun (m2: #IMeasurable) -> m1 + m2.Measure let inline ( |+| ) m1 m2 = (Overloads $ m1) m2 Not tested, since I don’t have IMeasurable, but it may … Read more
First of all, try to avoid list concatenation (@) whenever possible, since it’s O(N) instead of O(1) prepend. I’d start with a (relatively) easy to follow plan of how to compute the cartesian outer product of lists. Prepend each element of the first list to each sublist in the cartesian product of the remaining lists. … Read more
This is an interesting problem! I needed to implement exactly this in C# just recently for my article about grouping (because the type signature of the function is pretty similar to groupBy, so it can be used in LINQ query as the group by clause). The C# implementation was quite ugly though. Anyway, there must … Read more
The function is not particularly readably written, which may be the reason for your confusion. The construct (_::_)::_ is a pattern matching on value of type list of lists of ints that says that the first case should be run when you get a non-empty list of non-empty lists. The same thing can be written … Read more
Implementation which does not stack-overflows: let splitList list = List.foldBack (fun x (l,r) -> x::r, l) list ([],[])
The best answer is ‘neither’. 🙂 There’s some ugliness associated with both while loops and tail recursion. While loops require mutability and effects, and though I have nothing against using these in moderation, especially when encapsulated in the context of a local function, you do sometimes feel like you’re cluttering/uglifying your program when you start … Read more
It’s not explicitly writing the constraints that is the issue, it’s that the syntax is not so nice that you can place a member constraint on a parameter and then invoke the member in the usual way. The body of walk_the_creature and walk_the_creature2 would be the same here: let inline walk_the_creature_2 (creature:^a when ^a:(member Walk … Read more