_result can get bound to the wrong value in a breakpoint
Using test result001 in the example below.
:list shows that the tick is wrapping
map id xs (it is not appreciated here, but the said subexpression is highlighted in ghci).
_result seems to be bound to the value of
*Main> :b 1 20 Breakpoint 1 activated at result001.hs:1:12-20 *Main> f "abc" Stopped at result001.hs:1:12-20 _result :: Bool xs :: [a] ... [result001.hs:1:12-20] *Main> :list 1 f xs = case map id xs of 2  -> True ... [result001.hs:1:12-20] *Main> :fo _result *** Ignoring breakpoint _result = False