Question

I can do

for event in linq.Deltas do

or I can do

linq.Deltas |> Seq.iter(fun event ->

So I’m not sure if that is the same. If that is not the same I want to know the difference. I don’t know what to use: iter or for.

added – so if that is the matter of choice I prefer to use iter on a top level and for is for closures

added some later – looking like iter is map + ignore – it’s the way to run from using imperative ignore word. So it’s looking like functional way …

Answer 1

You can modify mutable variables from the body of a for loop. You can’t do that from a closure, which implies you can’t do that using iter. (Note: I’m talking about mutable variables declared outside of the for / iter. Local mutable variables are accessible.)

Considering that the point of iter is to perform some side effect, the difference can be important.

I personally seldom use iter, as I find for to be clearer.