Computing cyclomatic complexity with F# 5.0 interactive and Mono.Cecil

Many moons ago, I posted a simple PowerShell script to use the FxCop SDK to introspect over a bunch of assemblies and compute a measure of the cyclomatic complexity of each method; in this case, by counting the number of IL branch instructions that do not branch to the next instruction, and which have a distinct target from any other branch.

That in turn was based upon the algorithm used in NDepend 1.x, which was sufficiently antique to not consider switch opcodes, a deficiency which can be worked around. And as an alternative, the algorithm used in Mono.Gendarme can be implemented in F# instead.

The main barrier to creating a simple replacement with Mono.Cecil has been the location of the assemblies with the NuGet package version in the file path. Now, however, with F# 5.0 interactive allowing reference-to-nuget statements, providing a pair of scripts that can do the job, without the awkward question "Where's Cecil?", becomes a simple task.

The classic version first

and another using the algorithm from Mono.Gendarme