load-string doesn't work in for loop

Question

In REPL, this code worked just fine and gives the answer 36

(do
  (load-string (str "(def yyy" 2 " 18)"))
  (* 2 yyy2))

While it wouldn't work when I introduced a for loop into it

(do
 (for [x [1 2 3]]
  (load-string (str "(def yyyy" x " 18)")))
 (* 2 yyyy2))

The error said unable to resolve symbol yyyy2, which should have been defined within load-string. Can some expert explain the reason for me? Thanks!

Piotrek Bzdyl · Accepted Answer · 2017-06-15 18:41:27Z

2

for produces a lazy sequence thus load-string expression won't be evaluated until you force its evaluation. You can force it by wrapping for in dorun or doall.

For cases where you only need the side effects you should use doseq or when you just need to iterate over a range of numbers dotimes might also be handy.

edited Jun 15, 2017 at 18:41

answered Jun 14, 2017 at 17:57

Piotrek Bzdyl

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2 Comments

Sam Estep Over a year ago

Instead of wrapping for in dorun or doall, you should just replace for with doseq.

Piotrek Bzdyl Over a year ago

@SamEstep You're right - I have edited my answer. Thanks!

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