-> Maybe Module
-> [SCC ModSummary]
-- Calculate SCCs of the module graph, possibly dropping the hi-boot nodes
+-- The resulting list of strongly-connected-components is in topologically
+-- sorted order, starting with the module(s) at the bottom of the
+-- dependency graph (ie compile them first) and ending with the ones at
+-- the top.
--
-- Drop hi-boot nodes (first boolean arg)?
--