Question

While dabbling in Clojure I’ve written a very basic program to echo whatever the user types into it. However, it doesn’t run in a way that I’m perceiving to be natural. Here’s the code:

(defn goo []   (print 'echo> ')   (def resp (read-line))   (print resp) ) 

I would expect the code to run like this (for me typing in foo as the input to read-line):

user=> (goo) echo> foo foonil 

But instead, the echo and read-line is switched:

user=> (goo) foo echo> foonil 

Why does this happen? Is there a subtlety I’m missing?

EDIT: From Joe’s answer, the updated correct solution is:

(defn goo []   (print 'echo> ')   (flush)   (def resp (read-line))   (print resp)   (flush) ) 

Also, the flushes aren’t necessary if you use println instead of print.

Answer 1

I know nothing of clojure but this sounds like a case of buffers not getting flushed. Figure out how to flush standard out after the print. The println function probably flushes at the end of each line. Try:

(defn goo []   (print 'echo> ')   (flush )   (def resp (read-line))   (print resp) )