Debugging/Stepping into a package module via cabal repl - debugging

Question

So I have the following code from Preventing caching of computation in Criterion benchmark and my aim is to be able to step from main directly into the function defaultMain in Criterion.Main :
{-# OPTIONS -fno-full-laziness #-}
{-# OPTIONS_GHC -fno-cse #-}
{-# LANGUAGE BangPatterns #-}
module Main where
import Criterion.Main
import Data.List
num :: Int
num = 100000000
lst :: a -> [Int]
lst _ = [1,2..num]
myadd :: Int -> Int -> Int
myadd !x !y = let !result = x + y in
result
mysum = foldl' myadd 0
main :: IO ()
main = defaultMain [
bgroup "summation"
[bench "mysum" $ whnf (mysum . lst) ()]
]
and the cabal file is :
name: test
version: 0.1.0.0
build-type: Simple
cabal-version: >=1.10
executable test
main-is: Main.hs
build-depends: base >=4.8 && <4.9,
criterion==1.1.0.0
default-language: Haskell2010
ghc-options: "-O3"
(using ghc 7.10.1 and cabal 1.22.0.0).
If from within cabal repl I try to set a breakpoint in criterion I get the following error :
*Main> :break Criterion.Main.defaultMain
cannot set breakpoint on defaultMain: module Criterion.Main is not interpreted
Furthermore if I try to add the package I get the following error :
*Main> :add *Criterion
<no location info>: module ‘Criterion’ is a package module
Failed, modules loaded: Main.
If I do within the directory git clone https://github.com/bos/criterion
and then add the following two lines to my cabal file :
other-modules: Criterion
hs-source-dirs: .
./criterion
then upon doing cabal build I get the following errors :
criterion/Criterion/IO.hs:23:0:
error: missing binary operator before token "("
#if MIN_VERSION_binary(0, 6, 3)
so I suspect that I have to do a full on merge of the criterion cabal
file with my cabal file above, which feels a bit excessive.
Is there an easier way for me to go about setting a breakpoint
in Criterion, so that I can step (when debugging in cabal repl/ghci) directly from my source into criterion's source? Thanks
p.s. There is a related question at Debugging IO in a package module inside GHCi but unfortunately it did not help.

Answer 1

This is how I managed to achieve the desired goal of being able to step (within cabal repl) from my code into the criterion source :
First do :
mkdir /tmp/testCrit
cd /tmp/testCrit
Download criterion-1.1.0.0.tar.gz
Unzip into /tmp/testCrit, so we should have /tmp/testCrit/criterion-1.1.0.0. In this directory we have Criterion.hs etc.
Then jump into the folder containing the criterion source and do :
cd /tmp/testCrit/criterion-1.1.0.0
cabal sandbox init
cabal install -j
Note that this creates a directory : /tmp/testCrit/criterion-1.1.0.0/dist/dist-sandbox-782e42f0/build/autogen which we shall use later
Back in /tmp/testCrit create a Main.hs file containing the benchmark code above and also the cabal file above, but merge it with the criterion cabal file contained in /tmp/testCrit/criterion-1.1.0.0 in the following way. Note the main new additions are the lines :
cc-options: -fPIC
which allows one to run it in cabal repl, and the following
lines :
hs-source-dirs:
./
./criterion-1.1.0.0
./criterion-1.1.0.0/dist/dist-sandbox-782e42f0/build/autogen
The full cabal file should then look like :
name: test
version: 0.1.0.0
build-type: Simple
cabal-version: >=1.10
executable test
main-is: Main.hs
build-depends:
base >=4.8 && <4.9,
aeson >= 0.8,
ansi-wl-pprint >= 0.6.7.2,
base >= 4.5 && < 5,
binary >= 0.5.1.0,
bytestring >= 0.9 && < 1.0,
cassava >= 0.3.0.0,
containers,
deepseq >= 1.1.0.0,
directory,
filepath,
Glob >= 0.7.2,
hastache >= 0.6.0,
mtl >= 2,
mwc-random >= 0.8.0.3,
optparse-applicative >= 0.11,
parsec >= 3.1.0,
statistics >= 0.13.2.1,
text >= 0.11,
time,
transformers,
transformers-compat >= 0.4,
vector >= 0.7.1,
vector-algorithms >= 0.4
default-language: Haskell2010
ghc-options: "-O3"
c-sources:
./criterion-1.1.0.0/cbits/cycles.c
./criterion-1.1.0.0/cbits/time-posix.c
hs-source-dirs:
./
./criterion-1.1.0.0
./criterion-1.1.0.0/dist/dist-sandbox-782e42f0/build/autogen
cc-options: -fPIC
Then in the main directory do :
cd /tmp/testCrit/
cabal sandbox init
cabal install -j
Then we can spin up a cabal repl and step directly into
criterion from our Main.hs code :
*Main> :break Criterion.Main.defaultMain
Breakpoint 0 activated at criterion-1.1.0.0/Criterion/Main.hs:79:15-43
*Main> main
Stopped at criterion-1.1.0.0/Criterion/Main.hs:79:15-43
_result :: [Benchmark] -> IO () = _
[criterion-1.1.0.0/Criterion/Main.hs:79:15-43] *Main> :step
Stopped at criterion-1.1.0.0/Criterion/Main.hs:(131,1)-(147,39)
_result :: IO () = _
[criterion-1.1.0.0/Criterion/Main.hs:(131,1)-(147,39)] *Main> :step
Stopped at criterion-1.1.0.0/Criterion/Main.hs:(131,29)-(147,39)
_result :: IO () = _
bs :: [Benchmark] = [_]
defCfg :: Criterion.Types.Config = _
[criterion-1.1.0.0/Criterion/Main.hs:(131,29)-(147,39)] *Main> :step
Stopped at criterion-1.1.0.0/Criterion/Main.hs:132:10-37
_result :: IO Criterion.Main.Options.Mode = _
defCfg :: Criterion.Types.Config = _