Dependency on happy

[niklasbroberg]

HSE has an implicit dependency on happy for the parser. If happy isn't already installed then cabal install HSE doesn't work, it would be great if this could be fixed. This problem has shown up for real users trying to install both derive and hlint - failing when installing HSE because of the lack of happy.

Related to this deficiency in cabal-install: http://hackage.haskell.org/trac/hackage/ticket/227

[neapel]

bump

Configuring haskell-src-exts-1.14.0...
Failed to install haskell-src-exts-1.14.0
Last 10 lines of the build log:
[1 of 1] Compiling Main
Linking haskell-src-exts-1.14.0-80852/haskell-src-exts-1.14.0/dist/setup/setup ...
Configuring haskell-src-exts-1.14.0...
setup: The program happy version >=1.17 is required but it could not be found.
cabal: Error: some packages failed to install:
haskell-src-exts-1.14.0 failed during the configure step. The exception was:
ExitFailure 1

[UnkindPartition]

Corresponding cabal issue: haskell/cabal#220

[dead-claudia]

Another couple related Gitub issues, both depending on this package:

• Installing the required packages - missing happy? SublimeHaskell/SublimeHaskell#184
• The same solution for that fixed my errors in installing Fay.

[3noch]

Can't "happy" be declared as a system dependency, so at least cabal knows what's missing? This problem trickles down to dependents and can be very annoying to track down.

[mulchy]

+1 this should be added to the dependencies

[pjonsson]

All those who suggest that happy should be added to the dependencies: does that resolve your problem if happy is not in your path?

[3noch]

All that matters is that we know why the build failed.

[3noch]

To clarify, the build could fail much sooner in dependency resolution instead of build phase with an easy check: "I need happy; is it on the path? No. Fail immediately."

[pjonsson]

And I'm asking whether the build fails with a proper error message if you have happy installed but not in your path.

[UnkindPartition]

happy is an executable, not library. GHC doesn't track it in its package database, and you cannot depend on it in the cabal file (the dependency will never be satisfied, regardless of whether happy is installed and/or in PATH).

This issue isn't about adding a line to the cabal file. Rather it's about:

• waiting for (or helping!) cabal-install doesn't consider build-tools as dependencies haskell/cabal#220 to be addressed in some way
• building upon their solution

[Jeehut]

Hello, I just encountered a problem installing ghc-mod (this library couldn't be installed) and luckily could find the issue pretty quickly: I needed to install happy first. After running cabal install happy it all worked – so I agree with all my predecessors: happy should be added to the dependencies. The issue you are linking to still isn't solved either ... just saying.

[mpickering]

Fairly sure this is fixed now by Build-Tools dependencies.

[Arcanemagus]

Just a note, this isn't fixed yet as of the released version 1.20.2:

Failed to install haskell-src-exts-1.20.2
Build log ( /home/atom/.cabal/logs/haskell-src-exts-1.20.2.log ):
cabal: Entering directory '/tmp/cabal-tmp-855/haskell-src-exts-1.20.2'
Configuring haskell-src-exts-1.20.2...
cabal: The program 'happy' version >=1.19 is required but it could not be
found.
cabal: Leaving directory '/tmp/cabal-tmp-855/haskell-src-exts-1.20.2'

After manually running cabal install happy the building of haskell-src-exts worked correctly.