The APL lineage is generally extremely clever in the micro but completely normal levels of clever in the macro. and at the individual line level it's as easy a

The APL lineage is generally extremely clever in the micro but completely normal levels of clever in the macro. and at the individual line level it's as easy as any dynamic language to work your way through a head-scratcher by testing progressively larger chunks/stepping through with a debugger until you find where it starts breaking from your expectaions.