4 ms·
> Usually you combine this with pattern matching and other functional features and the whole thing makes it convenient in the end. That part is missing in C# Y
by CharlieDigital 1y ago
> Usually you combine this with pattern matching and other functional features and the whole thing makes it convenient in the end. That part is missing in C#
You mean like this?
string foo = result.MatchFirst(
value => value,
firstError => firstError.Description);
Or this?
ErrorOr<string> foo = result
.Then(val => val * 2)
.Then(val => $"The result is {val}");
Or this?
ErrorOr<string> foo = await result
.ThenDoAsync(val => Task.Delay(val))
.ThenDo(val => Console.WriteLine($"Finsihed waiting {val} seconds."))
.ThenDoAsync(val => Task.FromResult(val * 2))
.ThenDo(val => $"The result is {val}");
With pattern matching like this?
var holidays = new DateTime[] {...};
var output = new Appointment(
DayOfWeek.Friday,
new DateTime(2021, 09, 10, 22, 15, 0),
false
) switch
{
{ SocialRate: true } => 5,
{ Day: DayOfWeek.Sunday } => 25,
Appointment a when holidays.Contains(a.Time) => 25,
{ Day: DayOfWeek.Saturday } => 20,
{ Day: DayOfWeek.Friday, Time.Hour: > 12 } => 20,
{ Time.Hour: < 8 or >= 18 } => 15,
_ => 10,
};
C# pattern matching is pretty damn good[0] (seems you are not aware?).
[0] https://timdeschryver.dev/blog/pattern-matching-examples-in-csharp https://timdeschryver.dev/blog/pattern-matching-examples-in-...
- fabian2k 1y agoNone of your examples use native C# pattern matching. And without language support like e.g. discriminated unions you can't have exhaustive pattern matching in C#. So you'll have to silence the warnings about the missing default case or always add one, which is annoying.
- CharlieDigital 1y agoI mean, it's not a stretch to see how you can use native pattern matching with ErrorOr result types. #!/usr/local/share/dotnet/dotnet run #:package ErrorOr@2.0.1 using ErrorOr; var computeRiskFactor = ErrorOr<decimal> () => 0.5m; // Just an example var applyAdjustments = ErrorOr<decimal> (decimal baseRiskFactor) => baseRiskFactor + 0.1m; // Just an example var approvalDecision = computeRiskFactor() .Then(applyAdjustments) .Match( riskFactor => riskFactor switch { < 0.5m => "Approved", < 0.75m and >= 0.5m => "Approved with Conditions", >= 0.75m and < 0.9m => "Manual Review", _ => "Declined" }, errors => "Error computing risk factor" ); Console.WriteLine($"Loan application: {approvalDecision}"); (Fully contained program, BTW) Here's the OCaml version: let compute_risk_factor () = 0.5 let apply_adjustments base_risk_factor = base_risk_factor +. 0.1 let approval_decision = let risk_factor = compute_risk_factor () |> apply_adjustments in match risk_factor with | r when r < 0.5 -> "Approved" | r when r < 0.75 -> "Approved with Conditions" | r when r < 0.9 -> "Manual Review" | _ -> "Declined" let () = print_endline approval_decision Still not functional enough?...Or you just don't like C#? No point moving goal posts.