:l Test3.hs
-- set a break on the [] case in map
:b 1
-- trace an execution
:tr mymap (+1) [1,2]
:hist
:back
:show bindings
:back
:show bindings
:force _result
-- Run a GC so the BLACKHOLE indirection for _result (the AP_STACK) is removed,
-- ensuring _result now points directly to the value (in this case, the integer
-- 3).  This will be tagged, so we are checking that the pointer isn't naively
-- dereferenced to generate an unaligned load.
System.Mem.performGC
:back
:forward
-- at this point, we can't retrieve the bindings because _result (the AP_STACK)
-- was evaluated previously.  GHCi should not crash, preferably.