haskell - How to tap into hpc information during execution -

consider following use case: have quickcheck test suite consisting of 2 test cases prop_testcase1 , prop_testcase2. using hpc can observe code coverage of test suite.

however, i'd separate results coverage of prop_testcase1 , prop_testcase2 (to further process results). 1 way out run executable several times explicitly specifying test case command line argument , process generated tix file after each run.

yet, prefer hide away logic in library. in reality run more 2 test cases. explicitly re-executing binary each test case seems rather inconvenient. @ same time i'd imagine hpc keeps coverage data in kind of intermediate data structure during program execution.

question: there way recognize program has been compiled hpc symbols , somehow access data hpc generates @ runtime?

i think found way achieve desired effect. required functions provided trace.hpc.reflect module. unfortunately documentation lacking.

nevertheless, here minimal example seems work:

import trace.hpc.reflect  main :: io ()  main =    print (show $ f 5)   tix <- examinetix    print (show tix)   print (show $ f 6)   print (show $ f 7)   tix <- examinetix    print (show tix)   return ()   f x = x*2 

compile , run follows:

$ ghc -fhpc main [1 of 1] compiling main             ( main.hs, main.o ) linking main ... $ ./main "10" "tix [tixmodule \"main\" 3889152622 31 [1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1]]" "12" "14" "tix [tixmodule \"main\" 3889152622 31 [3,3,3,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, in1,1,1,1,0,0,0,0,0,1,1]]" 

so using can tap coverage data provided hpc while program executing.

if executable compiled without hpc support program still works tix object returned examinetix contains empty list.