On Dec 6, 11:28 am, samppi <[email protected]> wrote:
> I've read that loop/recur is less preferable to using higher-level
> function calls like reduce and for and map, especially when chunked
> seqs are implemented. But is can the loop below be rewritten to use
> those functions instead? It's a loop that iterates over one vector and
> changes both the vector and a map until a certain condition becomes
> true. I can't figure out how to use Clojure's high-level functions
> instead of loop/recur:
>
> (Let an-initial-vector be a vector; an-initial-map be a map; and
> modify-stack, modify-heads, and final-result be functions.)
>
> (loop [current-stack an-initial-vector
> current-heads an-initial-map
> current-index 0]
> (let [current-element (current-stack current-index)]
> (if (or (condition-true? current-element)
> (>= index (count current-stack)))
> (recur
> (update-in current-stack [current-index]
> modify-stack)
> (modify-heads current-heads current-element)
> (inc current-index))
> (final-result current-stack current-heads))))
>
> If it helps, it's possible that current-stack and current-heads to be
> merged into a single map that contains a :stack and a :heads key:
>
> (loop [current-data {:stack an-initial-vector
> :heads an-initial-map}
> current-index 0]
> (let [current-element ((:stack current-data)
> current-index)]
> (if (or (condition-true? current-element)
> (>= index (count current-stack)))
> (recur
> (-> current-data
> (update-in [:stack current-index] modify-stack)
> (update-in [:heads] modify-heads current-element))
> (inc current-index))
> (final-result current-data))))
How about this?
(let [v (take-while condition-true? an-initial-vector)
v (map modify-stack v)
m (reduce modify-heads an-initial-map v)]
(final-result v m))
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