Idris-dev-0.99.2 fails to install on Debian stretch

[nicolabotta]

After installing Idris 1.1.1 for test purposes, 0.99.2 fails to reinstall on Debian stretch. A problem appears to be src/Idris/DeepSeq.hs:

[ 37 of 108] Compiling Idris.Package.Common ( src/Idris/Package/Common.hs, dist/build/Idris/Package/Common.o )
[ 38 of 108] Compiling Idris.DeepSeq    ( src/Idris/DeepSeq.hs, dist/build/Idris/DeepSeq.o )

src/Idris/DeepSeq.hs:31:10: error:
    Duplicate instance declarations:
      instance NFData CT.Options -- Defined at src/Idris/DeepSeq.hs:31:10
      instance NFData CT.Options -- Defined in ‘Cheapskate.Types’

src/Idris/DeepSeq.hs:34:10: error:
    Duplicate instance declarations:
      instance NFData CT.ListType
        -- Defined at src/Idris/DeepSeq.hs:34:10
      instance NFData CT.ListType -- Defined in ‘Cheapskate.Types’

src/Idris/DeepSeq.hs:38:10: error:
    Duplicate instance declarations:
      instance NFData CT.CodeAttr
        -- Defined at src/Idris/DeepSeq.hs:38:10
      instance NFData CT.CodeAttr -- Defined in ‘Cheapskate.Types’

src/Idris/DeepSeq.hs:41:10: error:
    Duplicate instance declarations:
      instance NFData CT.NumWrapper
        -- Defined at src/Idris/DeepSeq.hs:41:10
      instance NFData CT.NumWrapper -- Defined in ‘Cheapskate.Types’
cabal: Leaving directory '.'
Failed to install idris-0.99.2
cabal: Error: some packages failed to install:
idris-0.99.2 failed during the building phase. The exception was:
ExitFailure 1
Makefile:18: recipe for target 'install' failed
make: *** [install] Error 1
nicola@cirrus:~/src/Idris-dev-0.99.2$

Any idea how to reinstall 0.99.2 on Debian stretch?

[melted]

That's because the version of cheapskate that 1.1.1 uses is too new for 0.99.2, but the upper bound is too high on 0.99.2 (a new incompatible version of cheapskate was released that added those instances that we already defined, unluckily with a version number under our upper bound.) So what you have to do is to add "cheapskate < 0.1.1" to the cabal install command line. Or to put that bound in idris.cabal.

[nicolabotta]

Thanks Niklas, your suggestion worked perfectly and I am closing the issue!