Extracting meta data from nupkg file with F# looks like C# Linq
Without being able to actually test (I can only guess what getDependencies, nugetPackagesFile, !! and filename are), something along the following should produce your desired set of dependencies:

getDependencies nugetPackagesFile
|&gt; Seq.collect (fun (name, ver) -&gt; 
       !! (sprintf "./src/packages/*/%s.%s.nupkg" name ver)
       |&gt; Seq.collect (fun pkg -&gt; NuGet.ZipPackage(pkg).GetFiles())
       |&gt; Seq.map (fun f -&gt; filename f.Path))
|&gt; Set.ofSeq


or, depending on your taste (kind of DFS vs. BFS)

getDependencies nugetPackagesFile
|&gt; Seq.collect (fun (name, ver) -&gt; !! (sprintf "./src/packages/*/%s.%s.nupkg" name ver))
|&gt; Seq.collect (fun pkg -&gt; NuGet.ZipPackage(pkg).GetFiles())
|&gt; Seq.map (fun f -&gt; filename f.Path)
|&gt; Set.ofSeq


where Seq.collect and map correspond to IEnumerable.SelectMany respectively Select in C#