[Haskell-cafe] No warning for unused import on first line
Tom Ellis
tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk
Sat Dec 6 20:01:13 UTC 2014
Using GHC 7.6.3, if I have
```
import Data.List
main :: IO ()
main = return ()
```
then I get a warning as expected.
```
% ghc -fforce-recomp -Wall test1.hs
[1 of 1] Compiling Main ( test1.hs, test1.o )
test1.hs:2:1: Warning:
The import of `Data.List' is redundant
except perhaps to import instances from `Data.List'
To import instances alone, use: import Data.List()
Linking test1 ...
```
However, if `import Data.List` appears on the first line, i.e. with no blank
line at the top of the file
```
import Data.List
main :: IO ()
main = return ()
```
then I get no warning.
```
% ghc -fforce-recomp -Wall test1.hs
[1 of 1] Compiling Main ( test1.hs, test1.o )
Linking test1 ...
```
Can anyone explain this?
Tom
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