(w/pipe "grep 'other'" (prn "other") (readlines))
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I've also changed w/pipe-from so it automatically redirects to stdin:
(w/pipe-from "ls -l" (readlines))
Ahhh, I got it... it's waiting for the pipe to close:
(w/pipe "grep 'other'" (prn "other") (close stdout) (readlines))
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