> What’s a example of these macros being used usefully? Sure, here are a couple examples I found from grepping my src directory. roguelikelike game I made for

> What’s a example of these macros being used usefully? Sure, here are a couple examples I found from grepping my src directory. roguelikelike game I made for a game jam: https://github.com/sjl/vintage/blob/master/src/main.lisp#L193 https://github.com/sjl/vintage/blob/master/src/main.lisp#L19... prolog compiler: https://github.com/sjl/temperance/blob/master/src/compiler/3-flattening.lisp#L115 https://github.com/sjl/temperance/blob/master/src/compiler/3... cl port of robotfindskitten: https://github.com/sjl/sattyrday/blob/master/src/002-afk/main.lisp#L213 https://github.com/sjl/sattyrday/blob/master/src/002-afk/mai... generative art lib: https://github.com/sjl/flax/blob/master/src/drawing/api.lisp#L153 https://github.com/sjl/flax/blob/master/src/drawing/api.lisp... https://github.com/sjl/flax/blob/master/src/looms/004-turtle-curves.lisp#L67 https://github.com/sjl/flax/blob/master/src/looms/004-turtle... There are plenty of other things that use various versions of these macros too. ASDF uses them all over the place. And of course Clojure code uses their versions. A Github search for when-let and if-let will give a lot of examples (though you have to wade through all the import matches... unfortunately Github search doesn't let you search for literal strings like "when-let (" to exclude those). > Why not use `if` and `when` directly? Convenience, especially when you have multiple in a row: (when-let ((a (foo)) (b (bar)) (c (baz))) (blah a b c)) ; => (let ((a (foo))) (when a (let ((b (bar))) (when b (let ((c (baz))) (when c (blah a b c))))))) > Is creating new names for variables — which is what `if-let` and `when-let` seems to contribute — that common of a pattern? I'm not sure what "new names for variables" means here. `let` (and these convenience macros) defines local variables. People create local variables for things pretty often.