guard

I have this code in Swift: guard let user = username else{ return nil } But I'm getting the following errors: Nil is incompatible with return type String Any of you knows why or how I return nil in this case? I'll really appreciate your help you have to tell the compiler that you want to return nil. How do you that? by assigning '?' after your object. For instance take a look at this code: func newFriend(friendDictionary: [String : String]) -> Friend? { guard let name = friendDictionary["name"], let age = friendDictionary["age"] else { return nil } let address = friendDictionary["address"]

I was just writing a quick bit of code, and I wanted to use the guard function in the IO Monad. However, there is no definition of MonadPlus for IO which means that we cannot use guard in IO land. I have seen an example of using the MabyeT transformer to use guard in the Maybe Monad and then lifting all of the IO actions but I do not really want to do that if I do not have to. Some example of what I want might be: handleFlags :: [Flag] -> IO () handleFlags flags = do when (Help `elem` flags) (putStrLn "Usage: program_name options...") guard (Help `elem` flags) ... do stuff ... return () I was

I am using: rails 5.1.5 guard 2.14.2 linuxmint Yesterday I installed guard, with the plugins livereload and minitest . I use guard to automate my tests and make sure nothing gets broken by mistake. I found out that for some reason, guard was not reacting to file changes. When it was first launched, it runned all tests, give me a prompt, and I had to press Enter in the prompt, and then, it start doing ALL THE TESTS again , each round takes about 1hr. After googling and trying everything I found, nothing seemed to work. So, I cool down my horses, and decided to play with guard. Problem found and

Back in November of 2016 I posted a question asking why I couldn't use guard to create an unwrapped version of a variable using the same name as the optional, like you can with if let: Link: Why isn't guard let foo = foo valid? When I wrote that question, the code below would fail to compile with an error that "Definition conflicts with previous value": //Test of using guard to create an unwrapped version of a var, like if let func guardTest(_ viewController: UIViewController?) -> UIViewController? { // Check if the current viewController exists print(String(describing: viewController)) guard

When launching Guard, I'm getting this output: $ guard WARN: Unresolved specs during Gem::Specification.reset: lumberjack (>= 1.0.2) ffi (>= 0.5.0) WARN: Clearing out unresolved specs. Please report a bug if this causes problems. What does this mean, and how do I fix it? Contents of Guardfile: guard 'livereload' do watch(%r{.+\.(css|js|html)$}) end guard 'sass', :input => 'css', :style => :compressed, :extension => '.min.css' jallen7usa I was seeing this issue by just running RSpec on its own. From what I understand, this means that you have more than one version of the listed gems installed