expanded readme

README.md

@@ -1,4 +1,77 @@
-
-
 # hsreduce
-Reducing Haskell programs for easier debugging of GHC bugs
+
+Reducing Haskell programs for easier debugging of GHC crashes or performance regressions.
+
+## Build Status
+
+[![GHC 8.10.1](https://github.com/dnlkrgr/hsreduce/actions/workflows/haskell.yml/badge.svg)](https://github.com/dnlkrgr/hsreduce/actions/workflows/haskell.yml)
+
+## Installing
+
+1. Clone the repo
+1. (Optional) Run `nix-shell`
+1. Run `cabal install` or `stack install`
+
+## Usage
+
+### Reducing
+
+The main use case of hsreduce is in reducing Haskell programs.
+hsreduce expects as inputs a single Haskell file and a shell script which outputs whether the file is interesting.
+
+Example:
+
+```bash
+hsreduce reduce --shellScript interesting.sh --testCase Bug.hs --numberOfThreads 4 --timeOut 30
+```
+
+Parameters:
+
+|Parameter        |Explanation                                      |
+|-----------------|-------------------------------------------------|
+|--shellScript    |path to the interestingness test                 |
+|--testCase       |path to the Haskell program you want to reduce   |
+|--numberOfThreads|self-explanatory                                 |
+|--timeout        |after how many seconds should tests be terminated|
+
+### How do I write interestingness tests?
+
+Example: Let's say you have a large Haskell file that prints "hello world" when you run it, but you're only interested in which part of the program makes it do that.
+I think a good interestingness test would look like this:
+
+```bash
+#!/usr/bin/env bash
+ghc Bug.s && ./Bug |& grep 'hello world'
+```
+
+### Merging
+
+Another use case is merging cabal projects into single Haskell files, which can then be reduced.
+
+Example:
+
+```bash
+hsreduce merge --projectType Executable --targetName containers
+```
+
+|Parameter        |Explanation                               |
+|-----------------|------------------------------------------|
+|--projectType    |enter either *Executable* or *Library*    |
+|--targetName     |name of the cabal target you want to merge|
+
+## FAQ
+
+**Q: I find this to be strange behaviour: "a shell script that returns exit code 0 if the file contains interesting behavior (reproduces a bug) and returns 1 otherwise ". Surely it makes more sense that something that checks for buggy behaviour returns a non-zero exitcode if it finds a bug?**
+
+A: You're correct.
+But here reproducing the bug is the "normal behavior" that we seek and anything else not.
+If a reduction is done that leads to a test case that crashes for another reason or leads to a timeout, then it's not "normal behavior".
+
+**Q: what do you mean by reduction?**
+
+A: By reduction I mean "making the Haskell file smaller to make it more easily readable by humans".
+This is done by trying to delete various elements from the Haskell program or by simplifying elements.
+
+## Other Questions
+
+Don't hesitate to message me on twitter.com/dnlkrgr

shell.nix

@@ -5,7 +5,7 @@ let
     name = "nixos-unstable-2020-12-25";
     url = "https://github.com/nixos/nixpkgs";
     ref = "refs/heads/nixos-unstable";
-    rev = "257cbbcd3ab7bd96f5d24d50adc807de7c82e06d";
+    rev = "102eb68ceecbbd32ab1906a53ef5a7269dc9794a";
   }) {};
 
 in

src/Merge/Merge.hs

@@ -36,12 +36,12 @@ import Util.Util
 
 
 hsmerge :: ProjectType -> T.Text -> IO ()
-hsmerge isExecutable targetName = do
+hsmerge projectType targetName = do
     let 
         filePath = "hie.yaml"
-        targetTypeS = case isExecutable of
-            Executable -> "exe"
-            Library -> "lib"
+        targetTypeS = case projectType of
+            Executable  -> "exe"
+            Library     -> "lib"
         fileContent = "cradle: {cabal: {component: \"" <> targetTypeS <> ":" <> targetName <> "\" }}"
 
     TIO.writeFile filePath fileContent

src/Reduce/Driver.hs

@@ -127,7 +127,8 @@ hsreduce' allActions (fromIntegral -> numberOfThreads) testAbs filePathAbs fileC
 
             when recordStatistics $ do 
 
-                perfStats <- mkPerformance (fromIntegral oldSize) (fromIntegral newSize) t1 t2 (fromIntegral numberOfThreads) successfulInvocations totalInvocations (getTokenDiff newState beginState) (getNameDiff newState beginState)
+                perfStats <- 
+                    mkPerformance (fromIntegral oldSize) (fromIntegral newSize) t1 t2 (fromIntegral numberOfThreads) successfulInvocations totalInvocations (getTokenDiff newState beginState) (getNameDiff newState beginState)
                 liftIO $ appendFile "hsreduce_performance.csv" $ show perfStats
 
                 liftIO 
@@ -175,6 +176,8 @@ deleteTempDirs numberOfThreads tChan = do
         t <- atomically $ readTChan tChan
         removeDirRecur t
 
+arst
+
 
 -- 1. check if the test-case is still interesting (it should be at the start of the loop!)
 -- 2. set alive variable to false