48 lines
1.2 KiB
Clojure
48 lines
1.2 KiB
Clojure
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"Macros are also just functions!"
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(defmacro hello [x]
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(str "Hello, " x))
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"Create a list and use it to be eval-ed at run time"
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(defmacro infix [form]
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(list (second form) (first form) (nth form 2)))
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"Sometimes it is easier to handcraft it ..."
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(defmacro infix-better [form]
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`(~(second form)
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__
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__ ))
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"Macro in a macro until you get a stack overflow! ;)"
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(defmacro r-infix [form]
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(list (second form)
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(if (instance? clojure.lang.PersistentList (first form))
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`(r-infix ~(first form))
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(first form))
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(if (instance? clojure.lang.PersistentList (nth form 2))
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`(r-infix ~(nth form 2))
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(nth form 2))
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))
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(meditations
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"Macros are just function eval-ed at compile time"
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(= "Hello, Macros!" (hello "Macros!"))
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"Can I haz some infix?"
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(= __ (infix (9 + 1)))
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"Remember these are nothing but code transformations"
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(= __ (macroexpand '(infix (9 + 1))))
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"You can do better than that, hand crafting ftw"
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(= __ (macroexpand '(infix-better (10 * 2))))
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"Things dont always work as you would like them to... "
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(= __ (macroexpand '(infix-better ( 10 + (2 * 3)))))
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"Really, you dont understand recursion until you understand recursion"
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(= __ (r-infix (10 + (2 * 3))))
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)
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