mrkkrp/megaparsec

Could megaparsec be installed with cabal 3.6 and ghc 8.10?

kalxd opened this issue · 2 comments

kalxd commented

Hi all, I installed cabal with ghcup tool:

$ ghcup list -c installed
✔✔ ghc   8.10.7   recommended,base-4.14.3.0 hls-powered
✔✔ cabal 3.6.2.0  latest,recommended

Adding megaparsec == 9.2.0 to the field build-depends of cabal file, try run cabal build, it shows:

$ cabal build
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: sample-0.1.0.0 (user goal)
[__1] trying: megaparsec-9.2.0 (dependency of sample)
[__2] trying: transformers-0.5.6.2/installed-0.5.6.2 (dependency of
megaparsec)
[__3] trying: scientific-0.3.7.0 (dependency of megaparsec)
[__4] next goal: primitive (dependency of scientific)
[__4] rejecting: primitive-0.6.4.0 (conflict: scientific => primitive>=0.7.1.0
&& <0.8)
[__4] skipping: primitive-0.6.1.1, primitive-0.6.1.0, primitive-0.5.4.0,
primitive-0.5.3.0, primitive-0.5.2.1, primitive-0.5.1.0, primitive-0.5.0.1,
primitive-0.5, primitive-0.4.1, primitive-0.4.0.1, primitive-0.4,
primitive-0.3.1, primitive-0.3, primitive-0.2.1, primitive-0.2, primitive-0.1,
primitive-0.6.3.0, primitive-0.6.2.0, primitive-0.6.1.2, primitive-0.6 (has
the same characteristics that caused the previous version to fail: excluded by
constraint '>=0.7.1.0 && <0.8' from 'scientific')
[__4] fail (backjumping, conflict set: primitive, scientific)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: scientific, base, megaparsec,
primitive, transformers, sample
Try running with --minimize-conflict-set to improve the error message.

I tried megaparsec 8.0 and megaparsec 7.0.5, also the same error. So how can I fix it? switching to other cabal versions?

thanks a lot.

mrkkrp commented

Well, this is weird. It fails because it doesn't find a version of primitive satisfying >= 0.7.1.0 && <0.8, but it doesn't even try 0.7.xxx versions, yet we can see that they are on Hackage:

https://hackage.haskell.org/package/primitive

Might be unrelated to Megaparsec. Can you show your cabal file? Did you try to run cabal update first?

kalxd commented

Well, It was installed correctly by switching cabal repository mirror.

It works very well now! thanks for your help. :)

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