Hi,
I'm just wondering if there's a clever way of creating a new map from
an existing map of map of maps.. with a key deep inside altered.
ie. given this map: {:a {:b {:c {:d 3}}}}
i want to create a new map, with the value at :d increased by 5.
I wrote a macro to do this, but it's quite ugly.
Thanks for the tip
-Patrick
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In case this helps at all, this is the macro that I wrote.
Usage: (set_map mymap [:a :b :c :d] (+ it 5))
(defmacro -set_map [mymap mykeys expr]
(let [syms (take (dec (count mykeys))
(repeatedly gensym))
bindings (interleave
(concat syms ['it])
(map list
mykeys
(concat [mymap] syms)))]
`(let [...@bindings]
~((fn assoc_fn [maps keys expr]
(if (empty? keys)
expr
`(assoc ~(first maps) ~(first keys)
~(assoc_fn (rest maps) (rest keys) expr))))
(concat [mymap] syms) mykeys expr))))
(defmacro set_map [map keys expr]
`(let [map# ~map]
(-set_map map# ~keys ~expr)))
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