Clojurians Log v2
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clojure 2026-08-31
hrtmt brng 2026-08-31T20:36:39.655239Z
I learnt a lesson. This code does not work:
(let [matcher (re-matcher #"a" "a")]
(loop [result :ignore]
(if (not (.find matcher))
result
(recur (for [_ [:ignore]]
(.group matcher 0))))))loop calls .find before for has a chance to consume the match.
seancorfield 2026-08-31T20:51:42.670179Z
Laziness and side-effects—an insidious combination!
dpsutton 2026-08-31T21:24:18.022339Z
that’s a neat little example
Ramin Soltanzadeh 2026-09-01T10:19:24.824669Z
Is it necessary to use not here to have recur be in the tail position?
dpsutton 2026-09-01T13:36:00.389109Z
no both branches of the if are tail position
dpsutton 2026-09-01T13:37:54.421729Z
(loop [counter 4]
(if (zero? counter)
:done
(if (even? counter)
(recur (dec counter))
(recur (dec counter)))))
:doneresult way down at the bottom is fordpsutton 2026-09-01T13:38:36.231389Z
(if condition
;; 45 lines doing tons of work
(....)
;; here at the bottom, 45 lines away happens when `not condition`, but hard to remember to connect back to it
result
)