transformers-0.5.6.2 from stack configuration does not match >=0.3 && ==0.2.* - haskell

Question

I'm trying to include quickcheck-instances package for testing. Here is how my dependencies field in package.yaml looks like:
dependencies:
- blackjack
- quickcheck-instances >= 0.3.25 && < 0.4
- QuickCheck >= 2.14.2 && < 2.15
Here is how my extra-deps field in stack.yaml looks like:
extra-deps:
- quickcheck-instances-0.3.25.2#sha256:083b84b91fccb3bbf22cd906f5bc731c8e6ee96c7554e892985452f2d61d4ad3,4484
- hashable-1.3.3.0#sha256:7f3b67151162a1dfe8472dc30430af98ed5470801d3f4b6c9b8d7a7443c920d4,4068
- unordered-containers-0.2.14.0#sha256:2fe789f78246b7c7ec10d7b85c72d898a9f72fdda5b60d581e839d21016bc628,4992
- QuickCheck-2.14.2#sha256:4ce29211223d5e6620ebceba34a3ca9ccf1c10c0cf387d48aea45599222ee5aa,7736
- case-insensitive-1.2.1.0#sha256:9dfd3171fc7698cf8d931727d3af3a7b389135b583e46b5adac1f9d2026fff61,2244
- data-fix-0.3.2#sha256:ca5ee8d5e15d08e65e9af74004cd663391706c0a62b7d1c6d0023e4c34cd0038,1659
- integer-logarithms-1.0.3.1#sha256:888fb6c4fbd79ed2e8f8b94b61bccac25f7fab2b13b32b496e86828bc60b17cf,3184
- old-time-1.1.0.3#sha256:c91fbb3ee73d20ccd015842b30f1f29a304893ebe0ae3128b7bbc13d5bb0d4c8,1328
- scientific-0.3.7.0#sha256:0f188a7b92780d81a2e3cf1195a3a24cfe3e7c43d0e9e0f2101a465803d68076,4773
- splitmix-0.1.0.3#sha256:fc3aae74c467f4b608050bef53aec17904a618731df9407e655d8f3bf8c32d5c,6049
- strict-0.4.0.1#sha256:50187e750751a258efea12ef2979e16a014a953c15bf4c2fca2f1168a44a5a12,4156
- tagged-0.8.6.1#sha256:29c67d98a4404607f024750ab9c7210dadcbbef4e1944c48c52902f2071b2662,2874
- these-1.1.1.1#sha256:bdc0a3015b2e5cdf016e402937d71856ae5fe4e9e9a0d4823cc94a214c55a39b,2732
- time-compat-1.9.6.1#sha256:cddf1a7654ccc3564d2197e6bf0064254abf792c591a9fa0eaa16e6039036152,4997
- uuid-types-1.0.5#sha256:5031383749d57cb95877d7e56f0300be66652b6e57f5ba6681dcc6e4f78d046d,2541
- vector-0.12.3.0#sha256:0ae2c1ba86f0077910be242ec6802cc3d7725fe7b2bea6987201aa3737b239b5,7953
- assoc-1.0.2#sha256:a824e4f615469a27ad949dbf4907ba258bd6b459deebec00524c7bcb3f65cc9f,1205
- base-orphans-0.8.5#sha256:b01baac1b88cc80e70214c064ec8c174718c19400232588bff591f5a9c49a750,3177
- old-locale-1.0.0.7#sha256:fa998be2c7e00cd26a6e9075bea790caaf3932caa3e9497ad69bc20380dd6911,1071
- primitive-0.7.2.0#sha256:d7c3635e83ae160129cdfe2be4092ab6389199d73a2c29adf904124dbcfe6100,2660
- random-1.2.0#sha256:195506fedaa7c31c1fa2a747e9b49b4a5d1f0b09dd8f1291f23a771656faeec3,6097
- bifunctors-5.5.11#sha256:cc425ee85aae56dba1123baf6fb3fa7abcd90782f26bb904eef14c7332ee85f6,3919
- comonad-5.0.8#sha256:1f1aabd73ec7f80f20cf078a748a60cd48d8e57277802fdf6a9ab3601a9b8f7e,3631
- th-abstraction-0.4.3.0#sha256:db4b3b69398acd8a7c5c8cc8a962da55d65d05d44d5039b51bd3cb5fb3d8400f,2148
- distributive-0.6.2.1#sha256:0f99f5541cca04acf89b64432b03422b6408e830a8dff30e6c4334ef1a48680c,2996
- indexed-traversable-0.1.1#sha256:e4602357513aa3b146546227732e6e5698392f4324ab690e109cc05676ba3b4f,2491
- transformers-compat-0.6.6#sha256:510709db2b12d1510d70de824ee544ca0a9e6f27aa7e299218cbacc0750b4a5e,5560
- transformers-0.5.6.2#sha256:6c959d14430f4deffb99579ba019de07c3d852a2122b6f449344386c7d75ff1d,3172
This is the error I got:
Error: While constructing the build plan, the following exceptions were encountered:
In the dependencies for transformers-compat-0.6.6:
transformers-0.5.6.2 from stack configuration does not match >=0.3 && ==0.2.*
needed due to blackjack-0.1.0.0 -> transformers-compat-0.6.6
Some different approaches to resolving this:
* Set 'allow-newer: true' in /home/xwtek/.stack/config.yaml to ignore all version constraints and build anyway.
Plan construction failed.
Of course after setting the allow-newer into true, it works, but I don't want to mess with that setting, because I fear that something like that would make things break later. Any better solution?

Answer 1

Clearly, you are missing how stack works. You should read the stack user guide, but let me explain briefly. stack uses two files to work:
stack.yaml: It defines from where stack should download packages. By default Stackage. Optionally, git repos, hackage or local libraries.
package.yaml: It defines which libraries you'll be using along with how to build your executable. Dependencies, compiler flags, test, etc...
In general the only thing you need to touch from stack.yaml is the resolver, and then use package.yaml to list your dependencies. So, How does stack.yaml is used?
You should have a line like this
resolver:
url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/6.yaml
This specifies the set of packages you gonna use, called: resolver or snapshot. All libraries version within an snapshot are guaranteed to build togheter with no dependency hell. In the example above the resolver is set to lts-18.6. So, If you visit stackage page for that snapshot you'll see all suported libraries and the compiler version: ghc-8.10.4
So let say I want to add QuickCheck to my dependencies. In my package.yaml I would list it down the library dependencies label
library:
dependencies:
- QuickCheck
The version of QuickCheck is determine by the selected resolver (18.6) which in this case is QuickCheck-2.14.2 as you can check in the stackage web. Of course, it is a good practise to specify the actual version in package.yaml
library:
dependencies:
- QuickCheck-2.14.2
But it is not necessary, since the resolver already sets the version from you. If you need another version of the package, then you have to add it to extra-deps, indicating stack that you want packages from lts-18.6 and a different package listed in extra-deps
The stack documentation is fairly good, so you should read it more carefully.