Console<RT>.readLine repeatedly returning same input without blocking

I modified the original example from https://github.com/louthy/language-ext/wiki/How-to-deal-with-side-effects#ioa which showcases the use of let:

var computation = from text  in readAllText(inpath)
                  let ntext = Capitalise(text)
                  from _     in writeAllText(outpath, ntext)
                  select unit;

to

var computation = repeat(from l in Console<RT>.readLine
                  let r = l + l
                  from _ in Console<RT>.writeLine(r)
                  select unit);

Expected

The computation should work as REPL which echos the input twice.

What happens

When I enter some chars and press Enter, the console is scrolling forever and repeats printing the output without waiting for new user input.

However, the following works:

var computation = repeat(from l in Console<RT>.readLine
                  from r in SuccessEff(l + l)
                  from _ in Console<RT>.writeLine(r)
                  select unit);

Am I doing something wrong or is this a bug?

[louthy]

FYI: I haven’t forgotten this, I’m just working on a more robust solution for the Aff and Eff monads to turn them into DSLs rather than use the Thunks, which are adding a bit too much complexity (and causing edge case issues like this, which in itself was caused by a fix to another issue).

[timmi-on-rails]

Thank you very much, I can confirm that both of my examples work as expected with version 4.1.0.