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reducers example isn't parallel

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Assessment

Difficulty
1/5
Estimated time
Under an hour
Newbie friendliness
55/100
Issue type
Documentation
Clarity
Clearly specified
Activity status
Stale
Tech stack
clojure
Domain
documentation

Research direction

Start at the reducers reference page linked in the issue and find the foldcat example using (range 100000). Update the example so it uses a vector for parallel folding and retain a concise explanatory comment; done means the page no longer presents a sequential range as a parallel example.

Written by the indexing model from the issue text.

Description

help wanted

The following example included in https://clojure.org/reference/reducers won't run in parallel because range is a seq:

(r/foldcat (r/filter even? (r/map inc (range 100000))))

It is confusing to find a "no-gain" example in a page explaining reducers.

Consequently, I'd suggest instead:

;; `vec` is there since seqs don't support parallel folding
(r/foldcat (r/filter even? (r/map inc (vec (range 100000)))))

Perhaps the comment would duplicate some information already in the page (If a collection does not support folding, it will fall back to non-parallel reduce instead.), but newcomers probably will appreciate a reminder (and an example).

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Forks
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