# Profiterole [![Hackage version](https://img.shields.io/hackage/v/profiterole.svg?label=Hackage)](https://hackage.haskell.org/package/profiterole) [![Stackage version](https://www.stackage.org/package/profiterole/badge/lts?label=Stackage)](https://www.stackage.org/package/profiterole) [![Linux Build Status](https://img.shields.io/travis/ndmitchell/profiterole.svg?label=Linux%20build)](https://travis-ci.org/ndmitchell/profiterole) [![Windows Build Status](https://img.shields.io/appveyor/ci/ndmitchell/profiterole.svg?label=Windows%20build)](https://ci.appveyor.com/project/ndmitchell/profiterole)

Script for reading and restructring a GHC profile script.

## The Goal

Given profile data, different ways of looking at it reveal different insights. This tool provides one of those insights - in addition to reading the standard profile output and using other tools such as [Profiteur](https://hackage.haskell.org/package/profiteur).

Profiterole aims to make the profile shorter by combining common subtrees and lifting them to the root - e.g. if you call `parseFile` from 7 places in the code, instead of having 7 pieces of `parseFile` profiling, Profiterole will give you one.

As an example compare [HLint profile input](https://gist.github.com/ndmitchell/308cd9a2774873c9a74ee613ae203b65#file-hlint-prof) to [HLint Profiterole output](https://gist.github.com/ndmitchell/ab790bbfa482a70fa2db020fda623309#file-hlint-profiterole-txt).

## Usage

To run, first install (`cabal update && cabal install profiterole`), generate a GHC profile the [normal way](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/profiling.html), then run:

    profiterole myprogram.prof

Profiterole will generate `myprogram.profiterole.txt` and `myprogram.profiterole.html` - both contain the same information, but the HTML has hyperlinks. There are three columns of numbers:

* `TOT` is the total time spent in any item under this code, what GHC calls inherited time.
* `INH` is the total time spent in the items that Profiterole did not move out to the top level.
* `IND` is the individual time, just like GHC profiles.

For large programs, using `+RTS -P` (instead of the common `-p`) will give more accurate results.