tee doesn't work within a loop

[YuanYuYuan]

Question

Hi there! I have a question about tee's behavior

echo "hello" | tee { save -a hello.log }

produces

───┬───────
 0 │ hello
───┴───────

But

for idx in 1..5 { echo "hello" | tee { save -a hello.log } }

prints nothing.

Both of them do save the message(s) into hello.log. Any advice would be greatly appreciated!

Additional context and details

No response

[fdncred]

Any ideas/thoughts @devyn?

[devyn]

I believe this is an issue with expressions in for, as they don't print (even on the REPL) in that case. If you use an explicit print, it should work:

> for idx in 1..5 { echo "hello" | tee { save -a hello.log } | print }
╭───┬───────╮
│ 0 │ hello │
╰───┴───────╯

╭───┬───────╮
│ 0 │ hello │
╰───┴───────╯

╭───┬───────╮
│ 0 │ hello │
╰───┴───────╯

╭───┬───────╮
│ 0 │ hello │
╰───┴───────╯

╭───┬───────╮
│ 0 │ hello │
╰───┴───────╯

Of course, at the moment, the tee command expects a stream, so your input gets converted to a list to make that happen. I will probably patch that sometime soon, as there really shouldn't be any difference between a text stream and a string.

[fdncred]

Right, for uses blocks and each uses closures. So, with each you can do this similar pipeline.

1..5 | each { echo "hello" | tee { save -a hello.log } }

[arnfaldur]

This issue can be closed.

[fdncred]

Thanks, ping us on discord if this needs to be reopened.