Permit zero content types for empty response

[jekor]

See haskell-servant/servant#69

Error:

    • Couldn't match type ‘'[]’ with ‘ct0 : cts0’
        arising from a use of ‘client’

Relevant code:

Delete '[] ()

[imalsogreg]

Thanks! I will try to get to this tonight EST

[imalsogreg]

@jekor Looking at newer servant-client code, I don't see special handling of () anymore - I believe this has been replaced by NoContent, and handlers over NoContent-returning endpoints permit zero content types. Does using NoContent work for you? If not, do you mind trying out kjd issue-51 branch? If it works we can think about merging it to master here, and discuss if servant-client should special-case () too as I think it used to.

https://github.com/haskell-servant/servant/blob/master/servant-client-core/src/Servant/Client/Core/Internal/HasClient.hs#L185-L241

[jekor]

Thanks. I've confirmed that the issue-51 branch compiles for me, but then I found out that '[] () will no longer compile with servant-server. I hadn't realized this, as the client gets compiled before the server in my build system.

NoContent works for me. Sorry for the distraction!