ghc-heap-view: Extract the heap representation of Haskell values and thunks
This library provides functions to introspect the Haskell heap, for example to investigate sharing and lazy evaluation. As this is tied to the internals of the compiler, it only works with specific versions. This version supports, GHC 8.8. For GHC 8.6 use version 0.6.0. For older GHC versions see ghc-heap-view-0.5.10.
It has been inspired by (and taken code from) the vacuum package and the GHCi debugger, but also allows to investigate thunks and other closures.
This package also provides a new GHCi-command, :printHeap
, which allows you
to inspect the current heap representation of a value, including sharing and
cyclic references. To enable the command, you need to load the included ghci
script or add it to ~/.ghci
, as explained by cabal install
. Once it is
set up, you can do this:
> let value = "A Value" > let x = (value, if head value == 'A' then value else "", cycle [True, False]) > :printHeap x let x1 = _bco x21 = [] in (x1,_bco,_bco) > length (take 100 (show x)) `seq` return () -- evaluate everything > :printHeap x let x1 = "A Value" x16 = True : False : x16 in (x1,x1,x16)
You can change the maximum recursion depth using :setPrintHeapDepth
:
> :setPrintHeapDepth 3 > :printHeap x let x1 = C# 'A' : ... : ... in (x1,x1,True : ... : ...)
If the view is impaired by blackholes (written _bh
), running
System.Mem.performGC
usually helps.
The work on this package has been supported by the Deutsche Telekom Stiftung (http://telekom-stiftung.de).
Flags
Automatic Flags
Name | Description | Default |
---|---|---|
prim-supports-any | The used GHC supports Any as an argument to foreign prim functions (GHC ticket #5931) | Disabled |
Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info
Downloads
- ghc-heap-view-0.6.4.1.tar.gz [browse] (Cabal source package)
- Package description (as included in the package)
Maintainer's Corner
For package maintainers and hackage trustees
Candidates
Versions [RSS] | 0.1, 0.2, 0.3, 0.3.0.1, 0.3.0.2, 0.3.0.3, 0.3.0.4, 0.4.0.0, 0.4.1.0, 0.4.2.0, 0.5, 0.5.0.1, 0.5.1, 0.5.2, 0.5.3, 0.5.4, 0.5.6, 0.5.7, 0.5.8, 0.5.9, 0.5.10, 0.5.11, 0.6.0, 0.6.1, 0.6.2, 0.6.3, 0.6.4, 0.6.4.1 |
---|---|
Dependencies | base (>=4.12 && <4.20), binary, bytestring (>=0.10.2), containers, ghc-heap, template-haskell, transformers [details] |
Tested with | ghc ==8.6.1, ghc ==8.6.2, ghc ==8.6.3, ghc ==8.6.4, ghc ==8.6.5, ghc ==8.8.1, ghc ==8.10.1, ghc ==9.0.1, ghc ==9.2.1, ghc ==9.2.8, ghc ==9.4.8, ghc ==9.6.3, ghc ==9.8.1 |
License | BSD-3-Clause |
Copyright | 2012-2019 Joachim Breitner |
Author | Joachim Breitner, Dennis Felsing |
Maintainer | Joachim Breitner <mail@joachim-breitner.de> |
Category | Debug, GHC |
Bug tracker | https://github.com/nomeata/ghc-heap-view |
Source repo | head: git clone git://git.nomeata.de/ghc-heap-view.git(Cabal) |
Uploaded | by JoachimBreitner at 2024-01-06T14:49:36Z |
Distributions | NixOS:0.6.4.1 |
Reverse Dependencies | 4 direct, 13 indirect [details] |
Downloads | 24102 total (92 in the last 30 days) |
Rating | (no votes yet) [estimated by Bayesian average] |
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Status | Docs available [build log] All reported builds failed as of 2024-01-06 [all 1 reports] |