Execute pipes line by line in fsi

Is your feature request related to a problem? Please describe.

When writing pipelines in fsi, they have to be executed as a single unit:

1   values
2   |> fun1
3   |> fun2

You need to select lines 1 to 3 to execute it, but you cannot execute line 1, then 2, then 3.

Describe the solution you’d like

It would give more flexibility to execute lines one by one. When a line starts with |>, it would interpret it as

it |> fun1

Executing the previous script line by line would be interpreted as:

let it = values
let it = it |> fun1
let it = it |> fun2

Describe alternatives you’ve considered

Continue to select multiple lines, but it’s easy to forget and get an error at execution.

[abonie]

Thanks, I think I understand the general idea. I doubt it is worth it though, but perhaps someone will want to take a stab at it.

My main concern is that this behavior would not always be desirable, and hence it will be tricky from UI perspective.

And on the other hand, it is fairly easy to achieve something like this already, by selecting only part of the pipeline expression to send to FSI (and taking advantage of the fact that alt+enter appends to whatever has already been typed in FSI, i.e. you can type it and then select |> fun2 in source and hit alt+enter, which will result in executing it |> fun2).

[smoothdeveloper]

One concern I see with such feature (which could be handy) is that I’d expect it to work for multiline expression that start with the prefix operator, without having to define the selection properly:

a
|> doSomething (fun b -> // evaluating on this line would also need to do the selection till the next pipeline
       ...
    )
|> ...

To nail it perfectly is probably not as simple as it seems, and we end up still needing to rely on user being mindful with how the interpreter is used across several individual evaluations, it won’t change this fact drastically IMO.