Mapping (spelt "Select" quite often in LINQ) is entirely normal and promoted going forwards. It can optimize extremely well for simple cases. By default it is not parallel and compiles to an underlying for loop.

Or you can use it with Tasks. https://itnext.io/fun-csharp-doing-linq-to-tasks-because-tas...

(caution: contains the M word)

More from Microsoft: https://devblogs.microsoft.com/pfxteam/tasks-monads-and-linq... ; referencing Lippert https://ericlippert.com/category/monads/

ContinueWith is not a broken "map". What people usually want is Select. https://learn.microsoft.com/en-us/dotnet/csharp/linq/standar...