metablog: if let it be

Swift packages this functionality in a combination if statement and let declaration:

 if let value = value {    print("value is \(value)") } 

This has a bunch of problems that are explained nicely in a Swift Evolution thread (via Michael Tsai) together with some proposals to fix it. One of the issues is the idiomatic repitition of the variable name, because typically you do want the same variable, just with less optionality. Alas, code-completion apparently doesn't handle this well, so the temptation is to pick a non-descriptive variable name.

In my previous post (Asynchronous Sequences and Polymorphic Streams) I noted how the fact that iteration in Smalltalk and Objecive-S is done via messages and blocks means that there is no separate concept of a "loop-variable", that is just an argument to the block.

Conditionals are handled the same way, with blocks and messages, but normally don't pass arguments to their argument blocks, because in normal conditionals those arguments would always be just the constants true or false. Not very interesting.

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