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ekmett / transformers-compat

transformers compatibility shim
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Provide Monad* instances from mtl for ExceptT #7

Closed jcpetruzza closed 8 years ago

jcpetruzza commented 10 years ago

Since mtl depends directly on transformers, it is not possible afaics for a project already depending on mtl to switch to ExceptT and remain compatible with transformers-0.3. The cost of the proposal would be to introduce a dependency on mtl, but I don't see to be problematic in practice.

Alternatively, one could a) make mtl depend on transformers-compat or b) put the instances in a mtl-compat package. I think a) will probably not fly since it would introduce a dependency on a non-HP package while b) would be a much worse solution due to orphan instances.

RyanGlScott commented 9 years ago

I attempted to implement idea (b) in my mtl-compat package. Does this suit your needs?

RyanGlScott commented 9 years ago

Never mind, transformers-compat now exports mtl instances, so this issue should be fixed without needing to use another package.

RyanGlScott commented 8 years ago

This has been fixed as of transformers-compat-0.4.