A lot of useful functions from FSharp.Core are now translated by WebSharper.

Async cancellation

• Proxies for CancellationTokenSource, CancellationToken, CancellationTokenRegistration.
• Proxies for Async class members: DefaultCancellationToken, CancelDefaultToken, CancellationToken, OnCancel, TryCancelled
• Async RPC calls are cancellable, the cancel continuation runs ASAP and the response are discarded.

MailboxProcessor

• Proxy handles timeout arguments and cancellation
• PostAndReply/TryPostAndReply methods are not supported as JS is single-threaded.

Printf

• Proxies for sprintf, printfn, failwithf, Printf.kbprintf
• %O uses JavaScript String(x) function
• %A generates a recursive pretty-printer for F# types if type information is available. Currently supports lists, unions, tuples, records, 1 and 2 dimensional arrays. Other types are sent to a dynamic pretty-printer.
• printfn prints to JavaScript console
• Printf.sprintf is not supported, use ExtraTopLevelOperators.sprintf instead.
• Printing as unsigned is not supported.

Fixes

• Fix #300: Server-side runtime error in some regional settings (for example Turkish)
• Fix #304: Converting string to char checks string length now
• Async.FromContinuations ensures that continuation is called only once, throws an error otherwise.

Breaking changes

• System.Web.HttpPostedFile type in Sitelets API have been changed to System.Web.HttpPostedFileBase to enable non-ASP.NET hosting (OWIN).

• Indexed properties in WIG: Previously if a property was defined with name "item", it translated to a an indexer on the object. This is changed so that the empty string is usable for this (still will get .NET property name Item, the default indexer for the class).

  // generates default .NET indexer
  "" =@ T<obj> |> Indexed T<int> // has JavaScript inline "$this[$index]"