My cabal build ended in a warning - yet not sure if this needs to be resolved or if build completed ?

Seems like build aborted over a warning ?

Below is the warning that seems to have aborted the build

src/Week01/EnglishAuction.hs:43:1: warning: [-Wunused-imports]
    The import of ‘IO’ from module ‘Playground.Contract’ is redundant

Do I need to ignore working, or force build to continue with warnings, or of course try and remedy the code causing the warning.

cabal build output

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2 Answers 2


Build was actually successful it seems - was just taken a back by the compiler warning.

I re-ran cabal build and then it just game me an output Up to date


This warning is not an error.
It was a complete build with some warning that could be ok in most of the cases. The compiler will tell you about unused variables or unused imports, like this case. Sometimes that is useful because it might lead you to identify an error.
This kind of warning are only shown the first time the file is compiled, that is why it didnt appear the second time you did the build.

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