Unable to synthetize type for point-free expression

[alexandrubuzea]

Your environment

Which OS do you use: Ubuntu 20.04

Steps to reproduce

In a Haskell file, define the function func as follows:

func = filter . (/=)

Expected behaviour

The synthetized type (suggested by language server) should be func :: Eq a => a -> [a] -> [a]. This definition works just fine in GHCi command line with the previously-mentioned result.

Actual behaviour

Instead, the following annotation is suggested:

func :: GHC.Types.Any -> [GHC.Types.Any] -> [GHC.Types.Any]

and an error marker is put for (/=), with the error Ambiguous type variable ‘a0’ arising from a use of /= prevents the constraint (Eq a0) from being solved.

[fendor]

Hi, thanks for the bug report!

Moving this to the main repo, as this feature is provided by HLS.