Add Result.requireTrue to take second parameter as a function

[sandeepc24]

Currently Result.requireTrue takes second parameter as a value, would it make sense to add an overloaded version or new extension method to allow it to take a function. This can be used in following scenarios

let trn = con.BeginTransaction()
let! result = cmd.AsyncExecute() |> Result.requireEqualTo 1 (fun x -> trn.Rollback(); "Error executing.")
trn.Commit()

[sandeepc24]

I think I need to use teeError.