Is this a bug of REPL or a intended feature?


OS : Windows 10 Home x64
Memory : 16GB
Processor : i7-7500U
Kotlin version 1.2.41 (JRE 1.8.0_161-b12)

I’m suffering with two problems.
First, REPL is initially too slow. It takes about 4 to 6 seconds for start. And It takes about three to four seconds for some of the first commands to be performed. It’s a bit annoying, but it can still be considered like warming up.

The most annoying issue is the redundant output as follow:

It doesn’t even do line break in some cases. I googled lot about this but couldn’t find. Is this just my problem? any others use this no problem? I reinstalled it but problem isn’t gone. What should I do to fix this?

Thank you.

PS. I did this not only with the powershell but also with cmd and the result was the same.
However, the REPL in IDEA were slow in speed too but no other problems.


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Sadly the Kotlin REPL is an incredibly buggy peace of software. I liked to show the REPL as an advantage of Kotlin of Java some time back, but today Java developers have the better tool at hand, called JShell.

Just write a simple file with a main method to make your experiments. The old Java way works best in Kotlin.