Large haskell program architecture

I've been doing job interviews lately and reviewing applicant's code has got me interested in quickly understanding abstractions and architectures in a novel codebase. My first step is now to draw a dependency graph -- read the code, and every time a module/function/file mentions a name, add a node for that name and an edge to the graph. This quickly builds up a picture of how the parts of the codebase are tied together. Easily-understood architectures have few edges. Bad architectures have edges from every node to every other node.

I've started applying this approach to larger programs I am considering adopting as well. For example, here is the dependency diagram for Pandoc, generated with

find pandoc/src -name '*.hs' | xargs stack exec graphmod -- -q -p | tred > graph.dot
dot graph.dot -Tsvg -ograph.svg