Imagine a map m {
"foo" [1 2 3 4]
"bar" [\a \b \c]
"baz" [true false]
}
How could I transform that into a seq s (
{"foo" 1 "bar" \a "baz" true}
{"foo" 1 "bar" \a "baz" false}
{"foo" 1 "bar" \b "baz" true}
{"foo" 1 "bar" \b "baz" false}
{"foo" 1 "bar" \c "baz" true}
{"foo" 1 "bar" \c "baz" false}
{"foo" 2 "bar" \a "baz" true}
...
)
I've made a macro to expand the map over a for:
(defmacro cartesian-map [m]
`(for ~(vec (reduce #(concat %1 %2) (map #(identity [(symbol %)
(list 'coordinates %)]) (keys coordinates))))
~(apply hash-map (flatten (map #(identity [% (symbol %)]) (keys
coordinates))))))
and expands correctly:
(clojure.core/for [foo (coordinates "foo") bar (coordinates "bar") baz
(coordinates "baz")] {"foo" foo, "bar" bar, "baz" baz})
but when I run it, I only get (), which doesn't make any sense because
if I run the expansion against the map m, it performs correctly.
Why would the macro expand correctly, but no run correctly in the
REPL? Also, are there any ways to simplify my macro?
Rob
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