I have some familiarity with Haskell, the language, but not so much with the toolchain. (I played around with Haskell before cabal and stack existed.) I'm told that stack is the tool I should be using to manage Haskell projects. I'm trying to learn the haste library, and I'm getting stymied on the first tutorial I've tried, because I can't get hplayground installed. I created a stack project; my stack.yaml has
extra-deps:
- ghc-simple-0.3
- haste-compiler-0.5.3
- shellmate-0.2.3
- haste-perch-0.1.0.9
- hplayground-0.1.3.1
and my .cabal file has hplayground listed in the build-depends. But when I run stack build, I get these errors:
Configuring haste-perch-0.1.0.9...
Building haste-perch-0.1.0.9...
Preprocessing library haste-perch-0.1.0.9...
Haste/Perch.hs:17:15: Warning:
-XOverlappingInstances is deprecated: instead use per-instance pragmas OVERLAPPING/OVERLAPPABLE/OVERLAPS
Haste/App/Perch.hs:18:15: Warning:
-XOverlappingInstances is deprecated: instead use per-instance pragmas OVERLAPPING/OVERLAPPABLE/OVERLAPS
[1 of 2] Compiling Haste.App.Perch ( Haste/App/Perch.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/Haste/App/Perch.o )
Haste/App/Perch.hs:61:15: Not in scope: ‘newTextElem’
Haste/App/Perch.hs:71:9:
Not in scope: ‘setAttr’
Perhaps you meant ‘jsSetAttr’ (imported from Haste.App)
Haste/App/Perch.hs:76:15:
Not in scope: ‘newElem’
Perhaps you meant one of these:
‘nelem’ (line 75), ‘notElem’ (imported from Prelude)
and a whole lot of similar errors. Any thoughts on what I'm doing wrong?
More broadly: what is a fast, easy way to get up and running with haste for someone who's not experienced with the Haskell toolchain?
Haste's event APIs got overhauled between the 0.4 and 0.5 series, and HPlayground is still on 0.4. If you want to use it, you will unfortunately have to fall back to 0.4 until HPlayground gets patched for 0.5.
For getting started in general, you should install the pre-build binaries if you're on a non-Linux platform (and probably if you're on a Linux platform as well, since you get man-pages and other niceties); the build process can be tricky and is prone to errors.
Once you've done that, you can refer to the docs and resources page on haste-lang.org, which contains links to API docs, video tutorials, source code examples and more.
Once you have installed ghc and cabal installed you will need to install the haste compiler as follows ( from http://haste-lang.org/downloads/ ):
$ cabal update
$ cabal install haste-compiler
$ haste-boot
After doing this, "hastec" ( the haste compiler ) should be available to use to compile haskell to javascript. In addition, "haste-cabal" ( the haste version of cabal ) should be available to use to install libraries such as haste-perch for use in your programs.
The readme file for haste-perch (https://github.com/agocorona/haste-perch) contains the instructions for installing haste-perch. Those instructions use "haste-inst" to install haste-perch but "haste-inst" is obsolete ( and no longer exists ). Use the modified instructions below to install haste-perch:
>git clone http://github.com/agocorona/haste-perch.git
>cd haste-perch
>haste-cabal install
I was able to install haste-perch and successfully build the example that it came with.
I also tried building hplayground but ran into compile problems that looked as if they were due to the code not being updated to use haste 0.5 . For example, "OnClick" was a valid identifier in earlier versions of haste but not anymore:
src/Haste/HPlay/View.hs:820:45:
Not in scope: data constructor ‘OnClick’
Perhaps you meant ‘Click’ (line 1017)
Related
I wanted to get going with Haskell a little bit and therefore took a look at the Spock framework. To start clean, I uninstalled everything Haskell related from my Arch Linux machine and installed ghcup, Cabal and Stack using the install scripts from their respective websites.
Now I want to follow Spock's Tutorial. Trying to install Spock globally with cabal install Spock as suggested gives me an error (abbreviated):
src/Web/Spock/Internal/Wire.hs:43:1: error:
Could not find module ‘Web.Routing.AbstractRouter’
Use -v (or `:set -v` in ghci) to see a list of the files searched for.
|
43 | import Web.Routing.AbstractRouter
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
cabal: Failed to build Spock-0.9.0.1. See the build log above for details.
I already found a question on reddit on the topic, but the solution does not apply because I'm not trying to use a specific version of the libraries as implied.
So I try to follow along and build only locally.
But when I reach the point where it says stack build --fast --pedantic, the build plan can not be constructed and Stack suggests to add another dependency, stm-containers. Doing so, I am presented with two additional suggestions for focus and primitive. When I add these, the plan fails again, this time without a simple solution:
In the dependencies for primitive-0.6.4.0:
base-4.13.0.0 from stack configuration does not match >=4.5 && <4.13 (latest matching version is 4.12.0.0)
needed due to Spock-example-0.1.0.0 -> primitive-0.6.4.0
I can do a little thing with Haskell, but with the build system(s), I am way out of my comfort zone. Help and hints appreciated. Oh, and all versions of course are the latest by the time of this post.
Due to incompatible versions of dependencies, Spock won't build with GHC 8.8 and above. A similar problem is described in Spock issue #149, though I'm not fully sure it is exactly the same incompatibility. The error you got from Stack hints at that, as base-4.13.0.0 is the version of base that is bundled with GHC 8.8. cabal-install failed in a more obscure way because, upon noting the incompatibility, it tries to solve the dependencies using older versions of Spock, eventually picking 0.9.0.1, attempting and, thanks to a missing version upper bound for the reroute dependency, failing to build it.
(Shortly after this answer was posted, the missing upper bound was retrofitted to the old Spock version, so attempting to reproduce the problem now will lead to an easier to understand failure.)
Casting the tutorial aside, the most straightforward way to use Spock given those complications is probably through cabal-install 3+. Begin by using ghcup to switch to GHC 8.6.5:
$ ghcup install 8.6.5
$ ghcup set 8.6.5
Then, create a blank project with cabal-install:
$ mkdir myproject
$ cd myproject
$ cabal init
Add Spock to the build-depends section of myproject.cabal:
build-depends: base >=4.12 && <4.13
, Spock == 0.13.*
Finally, you can run:
$ cabal build
Which will install Spock and its dependencies before building the project. (Note that you generally don't need to use cabal install to install libraries with cabal-install 3.)
It is presumably possible to make it work with Stack as well, by changing to the lts-14.27 resolver (the latest one that uses GHC 8.6.5), tracking down all dependency versions that need to be overriden (as you had began to do) and manually adding them to the extra-deps of stack.yaml.
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How does stack resolve dependecy conflicts?
I just started off with Haskell and I have few questions on how stack resolves dependencies.
Let's say my project requires lib A and lib B.
Internally, lib A requires lib X-1.9.0 and lib B requires lib X-2.0.0, how would stack resolve this?
stack documentation says they use snapshots to resolve conflicts, how does that work? Does it mean authors of lib A and lib B decide on a version of lib X which works with both of them? If so, what happens when I use a newer version of lib A or lib B or if either of them are not in the snapshots?
How are snapshots actually made?
Stack by default installs packages globally. What happens when a Project A requires lib Y-1.0 and Project B requries lib Y-1.1? How does this gets taken care of?
How does one use packages at "stackage.org"?
I was trying to install beam-core and google took me to https://www.stackage.org/package/beam-core where there's no mention of the command which installs it or what is the latest version. I could not find the version number anywhere expect in github releases.
With both pip and npm, it's quite straight forward and all the information on how to install and use is available on package's page. For example both,
https://pypi.org/project/bencode.py/
https://www.npmjs.com/package/projects
contains version number and install command, even though they are quite obvious.
I often get errors related to 'stack-configuration' when I try to install a package. I don't what 'stack-configuration' is?
What does all these errors mean and how to resolve them in context with all the above questions?
Performing stack install beam-core or stack repl --package beam-core --package beam-sqlite --package sqlite-simple --package beam-migrate --package text results in
`Users/username/Documents/beam-learn/beam-learn.cabal was modified manually. Ignoring /Users/username/Documents/beam-learn/package.yaml in favor of the cabal file.
If you want to use the package.yaml file instead of the cabal file,
then please delete the cabal file.
Stack has not been tested with GHC versions above 8.6, and using 8.8.2, this may fail
Stack has not been tested with Cabal versions above 2.4, but version 3.0.1.0 was found, this may fail
Error: While constructing the build plan, the following exceptions were encountered:
In the dependencies for hashable-1.2.7.0:
base-4.13.0.0 from stack configuration does not match >=4.4 && <4.13 (latest matching version is 4.12.0.0)
needed due to beam-core-0.8.1.0 -> hashable-1.2.7.0
Some different approaches to resolving this:
* Set 'allow-newer: true' in /Users/username/.stack/config.yaml to ignore all version constraints and build anyway.
* Build requires unattainable version of base. Since base is a part of GHC, you most likely need to use a different GHC version with the matching base.
Plan construction failed.`
For question #1:
Stack is designed around the concept that, for a given Stack project, only one version of a given package will be used. So, if you have a project that requires libraries A and B, and each of them depend on different versions of library X, then you cannot build your project as-is with Stack.
Snapshots are constructed by building collections of versions of packages (with exactly one version per package) such that all inter-package dependencies can be satisfied. This is done by the Stackage "curators" as described here using the curator tool. The curator tool uses the index of packages available on Hackage to construct a set of versions of packages (exactly one version per package) that are compatible in the sense that all package interdependencies are satisfied.
So, the library authors don't need to decide on a version of X that works with both. Rather, they need to specify a range of versions of X that their package works with, and the curator tool selects the most recent version of X that works with both their packages, as well as everyone else's packages that depend on X or on which X has a dependency.
If you want to use a newer version of library A or B that isn't in the snapshot, you add it as an extra dependency in your build plan (i.e., in the extra-deps section of your stack.yaml file). If the new version can't be built with the snapshot's version of X, you need to add an extra dependency for X too. If that breaks other packages and you can't find a set of extra dependencies that resolves all conflicts, you're out of luck.
In practice, because most packages have relatively generous ranges of dependencies and, for actively maintained packages, those ranges are generally kept up to date with newer compatible dependency versions, you don't often run into unresolvable conflicts, but it does happen.
For question #2:
Stack doesn't really install packages globally. It installs snapshot packages in a global cache (on Linux, in the directory ~/.stack) organized by snapshot. So, multiple versions can be installed in this cache under different snapshots, and the project will use whichever version is appropriate for the project's selected snapshot.
For question #3:
On the Stackage page for beam-core, you can see that the most recent LTS snapshot that contains it is lts-14.27. You can create a new project using this resolver with:
$ stack new --resolver lts-14.27 my-beam-project
To add beam-core to your project, edit my-beam-project/package.yaml and add a dependency:
dependencies:
- base >= 4.7 && < 5
- beam-core # <-- add this
Now, run stack build in your my-beam-project directory:
$ cd my-beam-project
$ stack build
It will build beam-core and all its dependencies which takes a few minutes, unless you've built beam-core for this snapshot before.
You can fiddle around with beam-core by running stack ghci in your project:
$ stack ghci
...
Configuring GHCi with the following packages: my-beam-project
GHCi, version 8.6.5: http://www.haskell.org/ghc/ :? for help
[1 of 2] Compiling Lib ( /u/buhr/src/overflow/my-beam-project/src/Lib.hs, interpreted )
[2 of 2] Compiling Main ( /u/buhr/src/overflow/my-beam-project/app/Main.hs, interpreted )
Ok, two modules loaded.
Loaded GHCi configuration from /tmp/haskell-stack-ghci/e5a80991/ghci-script
*Main Lib> import Database.Beam
*Main Lib Database.Beam> :t fieldName
fieldName
:: Functor f =>
(text-1.2.3.1:Data.Text.Internal.Text
-> f text-1.2.3.1:Data.Text.Internal.Text)
-> TableField table ty -> f (TableField table ty)
*Main Lib Database.Beam>
and, of course, you can add code in src/Lib.hs and/or app/Main.hs using the beam-core package.
For question #4:
As noted in a comment, I believe the problem you're encountering is that the most recent LTS is lts-15.3, and beam-core is not currently being built for this snapshot.
Because beam-core was built for previous snapshots but isn't being built for the current snapshot, there's probably a good reason it's been left out. In this case, it looks like the maintainer has not upgraded it to work with the latest GHC versions. Specifically, the latest version of beam-core-0.8.0.0 requires a version of hashable < 1.3, but the latest version satisfying that constraint is hashable-1.2.7.0 which requires base < 4.13. And, while it's far from obvious, that means it doesn't work with GHC 8.8, only GHC 8.6, so you have to go back to a GHC 8.6-series Stackage snapshot.
I'm trying to include a specific version of a library in a Haskell project. The library is bed-and-breakfast (which is used for martix operations), but I need the specific version 0.4.3 which fixed a bug with the multiplication implementation.
So, my stack.yaml looks like this:
flags: {}
extra-package-dbs: []
packages:
- .
extra-deps:
- bed-and-breakfast-0.4
- base-4.6.0.1
resolver: lts-12.8
But I'm getting this error when building:
Error: While constructing the build plan, the following exceptions were encountered:
In the dependencies for bed-and-breakfast-0.4:
base-4.11.1.0 from stack configuration does not match >=4.5 && <4.7 (latest matching version
is 4.6.0.1)
needed due to realworldhaskell-0.1.0.0 -> bed-and-breakfast-0.4
Some different approaches to resolving this:
* Set 'allow-newer: true' to ignore all version constraints and build anyway.
* Consider trying 'stack solver', which uses the cabal-install solver to attempt to find some
working build configuration. This can be convenient when dealing with many complicated
constraint errors, but results may be unpredictable.
* Recommended action: try adding the following to your extra-deps
in C:\Users\info\Desktop\Projects\haskell\stack.yaml:
- base-4.6.0.1
I've done the recommended action but it didn't solve anything. I've tried using different resolvers to see if it's an issue with my GHCi version but nothings worked. What is the best way to interpret error messages like this and how should I proceed?
EDIT:
If I remove -base.4.6.0.1 and add allow-newer: true I get this:
WARNING: Ignoring out of range dependency (allow-newer enabled): base-4.11.1.0. bed-and-breakfast requires: >=4.5 && <4.7
bed-and-breakfast-0.4: configure
Progress 1/2
-- While building custom Setup.hs for package bed-and-breakfast-0.4 using:
C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_Z6RU0evB_2.2.0.1_ghc-8.4.3.exe --builddir=.stack-work\dist\7d103d30 configure --with-ghc=C:\Users\info\AppData\Local\Programs\stack\x86_64-windows\ghc-8.4.3\bin\ghc.EXE --with-g
hc-pkg=C:\Users\info\AppData\Local\Programs\stack\x86_64-windows\ghc-8.4.3\bin\ghc-pkg.EXE --user --package-db=clear --package-db=global --package-db=C:\sr\snapshots\76fd1958\pkgdb --package-db=C:\Users\info\Desktop\Projects\haskell\
.stack-work\install\8c390635\pkgdb --libdir=C:\Users\info\Desktop\Projects\haskell\.stack-work\install\8c390635\lib --bindir=C:\Users\info\Desktop\Projects\haskell\.stack-work\install\8c390635\bin --datadir=C:\Users\info\Desktop\Proj
ects\haskell\.stack-work\install\8c390635\share --libexecdir=C:\Users\info\Desktop\Projects\haskell\.stack-work\install\8c390635\libexec --sysconfdir=C:\Users\info\Desktop\Projects\haskell\.stack-work\install\8c390635\etc --docdir=C:
\Users\info\Desktop\Projects\haskell\.stack-work\install\8c390635\doc\bed-and-breakfast-0.4 --htmldir=C:\Users\info\Desktop\Projects\haskell\.stack-work\install\8c390635\doc\bed-and-breakfast-0.4 --haddockdir=C:\Users\info\Desktop\Pr
ojects\haskell\.stack-work\install\8c390635\doc\bed-and-breakfast-0.4 --dependency=array=array-0.5.2.0 --dependency=base=base-4.11.1.0 --dependency=binary=binary-0.8.5.1 --dependency=deepseq=deepseq-1.4.3.0 --dependency=template-hask
ell=template-haskell-2.13.0.0 --extra-include-dirs=C:\Users\info\AppData\Local\Programs\stack\x86_64-windows\msys2-20150512\mingw64\include --extra-lib-dirs=C:\Users\info\AppData\Local\Programs\stack\x86_64-windows\msys2-20150512\min
gw64\bin --extra-lib-dirs=C:\Users\info\AppData\Local\Programs\stack\x86_64-windows\msys2-20150512\mingw64\lib --exact-configuration
Process exited with code: ExitFailure 1
Logs have been written to: C:\Users\info\Desktop\Projects\haskell\.stack-work\logs\bed-and-breakfast-0.4.log
Configuring bed-and-breakfast-0.4...
Cabal-simple_Z6RU0evB_2.2.0.1_ghc-8.4.3.exe: The package has an impossible
version range for a dependency on an internal library: bed-and-breakfast
==0.3.2. This version range does not include the current package, and must be
removed as the current package's library will always be used.
EDIT 2:
Ok, so I'm guessing that the bed-and-breakfast library needs base 4.11.1.0 which is included in GHCi 6.10.2 (according to https://wiki.haskell.org/Base_package) so I need a resolver which matches that GHCi version. Where can I find out what resolver version that is?
Here is the constraint on the latest available bed-and-breakfast package: base (>=4.5 && <4.7), which means it will likely not even compile with GHC version higher then 7.6. Considering that there is even no LTS snapshot prior to GHC 7.8, you are out of luck with that package.
To say it in another words, the package is outdated and your choices are:
submit an issue and hope maintainer will do something about it
try to make it work with newer ghc yourself
Use a different package
I am attempting to install the code for "Haskell: The Craft of Functional Programming", 3rd edition.
I'm using GHCi, version 7.6.3 on Centos version 7.
Then:
cabal unpack Craft3e
cd Craft3e-0.1.1.0/
cabal install
...
[29 of 67] Compiling CalcParseLib ( Calculator/CalcParseLib.hs, dist/build/CalcParseLib.o )
Calculator/CalcParseLib.hs:132:10:
Not in scope: type constructor or class `Applicative'
Failed to install Craft3e-0.1.1.0
cabal: Error: some packages failed to install:
Craft3e-0.1.1.0 failed during the building phase. The exception was:
ExitFailure 1
I have attempted this installation multiple times, but cannot
overcome this error.
Could I use something other than "cabal install"?
I have plenty to learn about Haskell before I get to this example,
but it would be great to know the installation is fine! :)
You have three options:
Install an older version of the Craft3e package, with e.g. cabal unpack Craft3e-0.1.0.10.
Find Calculator/CalcParseLib.hs in the source files you have downloaded with cabal unpack and add a...
import Control.Applicative
... line next to the other import lines at the beginning. I suspect you will have to do the same with other modules, if the same error shows up elsewhere after you do this change, and there might be other issues of a similar nature.
Install a newer version of GHC (7.6.3 is from 2013). Though the default CentOS repositories won't offer that, there are other options, such as an unofficial Fedora repository and a manual installation. See this page for instructions.
#3 is the definitive solution. If you just want to get started with the book right now, though, you can go for #1 and leave the reinstall for later.
For the sake of reference, here is a brief explanation of the problem (I will use some unfamiliar terms, but you will soon enough learn about them as you study Haskell). There is an important type class called Applicative which, for historical reasons, wasn't as well integrated with the rest of the core libraries as it should be. This situation was corrected in GHC 7.10, which both included Applicative in the Prelude (the module which is imported by default in Haskell programs) and made it necessary to add Applicative instances in a number of places where they were missing. The code in the Craft3e package was updated so that these Applicative instances were in place (cf. this entry in the book's blog), but the import Control.Applicative line, which would be necessary to make the updated code work in older GHCs that do not have Applicative in the Prelude, wasn't added, leading to the error that you are seeing.
I'm starting a new project that will hopefully use gtk2hs. However, I can not get this package to install on my fairly typical Linux box. Here is the failure :
[1 of 2] Compiling SetupWrapper ( /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs, /tmp/cairo-0.12.4-4201/cairo-0.12.4/dist/dist-sandbox-58b5f9c6/setup/SetupWrapper.o )
/tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:94:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:8:1-32
/tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:95:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:8:1-32
Failed to install cairo-0.12.4
[1 of 2] Compiling SetupWrapper ( /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs, /tmp/glib-0.12.4-4201/glib-0.12.4/dist/dist-sandbox-58b5f9c6/setup/SetupWrapper.o )
/tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:94:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:8:1-32
/tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:95:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:8:1-32
Failed to install glib-0.12.4
It seems to be related to recent cabal versions, since that used to work before. It seems to be a known bug (http://trac.haskell.org/gtk2hs/ticket/1292 , http://trac.haskell.org/gtk2hs/ticket/1291 and http://trac.haskell.org/gtk2hs/ticket/1289), however it has not moved for weeks. I am not sufficiently competent to suggest a good fix, so I would like your advice. This is very annoying since I am stuck on this important project, and it pains me to think that the main GUI lib of our language has been broken for many weeks now.
cabal-install version 1.18.0.2 using version 1.18.1.1 of the Cabal library / ghc 7.4.1
Thanks for your help
The correct solution for now is to build from darcs. Detailed instructions are given in the Getting the latest and greatest section of the installation instructions; the short version is:
darcs get --lazy http://code.haskell.org/gtk2hs
cd gtk2hs
sh bootstrap.sh
EDIT: The official 0.12.5 release of gtk2hs from December 2013 supports cabal 1.18, so the above darcs instructions are no longer needed. The full installation instructions are still available from the Gtk2Hs download page; the short version is:
cabal install gtk2hs-buildtools
cabal install gtk gtk3
You can try with older Cabal version using cabal install --cabal-lib-version=1.16.0 gtk.