Thanks Nicolas,
your first variant resembles the generated code much closer than my
initial approach, which is great. I need the eval though, to be able
to pass in non literals. In my real program I'm reading the
instructions from a binary file. So if I want to be able to do
something like this:
(def three-instructions '([+ 2 3] [- 0 1] [+ 1 0]))
(def compiled (compile-instructions three-instructions))
The macro would have to look like this:
(defmacro compile-instructions
[instructions]
(let [memory (gensym "memory-")]
`(fn [~memory]
~@(map (fn [[op m1 m2]]
`(aset ~memory ~m1 (~op (aget ~memory ~m1) (aget
~memory ~m2))))
(eval instructions)))))
But I like your suggestion to turn it into a function even better:
(defn compile-instructions
[instructions]
(let [memory (gensym "memory-")]
(eval
`(fn [~memory]
~@(map (fn [[op m1 m2]]
`(aset ~memory ~m1 (~op (aget ~memory ~m1) (aget ~memory ~m2))))
instructions)))))
And
(def compiled (compile-instructions three-instructions)))
just works as before. So I guess macros don't add any value here.
> eval is evil, but eval is not evil is a compiler (you have to evaluate the
> code you read).
> However eval is evil again in an "embedded compiler", when you use macro to
> extend Clojure.
What do you mean by "embedded compiler"?
Eugen
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