[Haskell-cafe] How to understand `|` in this code snippet ?

xxxMain = do timeout <- getEnv "xxx_TIMEOUT" case timeout of Just str | [(t, _)] <- reads str -> do addTimeout t (hPutStrLn stderr "*** TIMEOUT" >> _exit 1) return () _ -> return () ....... What does the `|` mean in "Just str | [(t, _)] <- reads str" ? Is it a logical `or` ? Sincerely! ----- fac n = let { f = foldr (*) 1 [1..n] } in f -- View this message in context: http://old.nabble.com/How-to-understand-%60%7C%60-in-this-code-snippet---tp2... Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.