RFC for `if let` expression // Посетен на 4 декември 2014. The `if let` construct is based on the precedent set by Swift, which introduced its own `if let` statement.
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Lattner, Chris. Chris Lattner's Homepage // Chris Lattner, 3 юни 2014. Посетен на 3 юни 2014. I started work on the Swift Programming Language in July of 2010. I implemented much of the basic language structure, with only a few people knowing of its existence. A few other (amazing) people started contributing in earnest late in 2011, and it became a major focus for the Apple Developer Tools group in July 2013 [...] drawing ideas from Objective-C, Rust, Haskell, Ruby, Python, C#, CLU, and far too many others to list.
