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Evaluate a Sequence (Seq.force ?)
f#

I kept looking for an easy way to force a sequence to evaluate. In this case, because I am passing in a print function that returns unit, I get back a seq<unit> and I just want it to evaluate and ignore it.

This works:

forEachRow tableId printRow |> Seq.to_list |> ignore

Is this more efficient because it will not build a list in memory:

forEachRow tableId printRow |> Seq.iter (fun()->())

I kept looking for something that would force the sequence to evaluate. Something like:

forEachRow tableId printRow |> Seq.force |> ignore

.

Seq.length

By on 9/3/2009 1:22 PM ()

Seq.length

And incur the overhead of an accumulator? Oh, the calls inside iter cost something too? Nevermind then.

By on 9/3/2009 1:46 PM ()

Seq.length

And incur the overhead of an accumulator? Oh, the calls inside iter cost something too? Nevermind then.

Well, if you really want to avoid all overhead, probably something like (browser coding, never compiled):

let inline Force (s:seq<_>) =

use e = s.GetEnumerator()

while e.MoveNext() do ()

would be best.

By on 9/3/2009 2:05 PM ()

What's wring with "Seq.iter ignore"?

By on 9/3/2009 12:06 PM ()

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