[Haskell] README.md instructions don't work OOTB

[mandrean]

Description

The example instructions for creating a client and a server in README.md don't work OOTB. Not for client nor server.

Swagger-codegen version

v2.2.2 or latest master, doesn't matter.

Swagger declaration file content or url

Tried with both a large/complex company-private Swagger, and the Petstore sample:
sh ./bin/haskell-servant-petstore.sh
cd samples/server/petstore/haskell-servant

Same results either way.

Steps to reproduce

0. git clone https://github.com/swagger-api/swagger-codegen && cd swagger-codegen
1. git checkout origin master && git pull origin master --rebase
2. mvn clean package
3. sh ./bin/haskell-servant-petstore.sh
4. cd samples/server/petstore/haskell-servant
5. stack install
6. Create a Main.hs file and try to import/use the generated client or server using the example code from the README.md, i.e:

{-# LANGUAGE RecordWildCards #-}

module Main where

import SwaggerPetstore.API

main :: IO ()
main = do
  SwaggerPetstoreBackend{..} <- createSwaggerPetstoreClient (ServerConfig "localhost" 8080)
  return ()

Results

Main.hs:9:33:
    Couldn't match expected type ‘ServerConfig
                                  -> IO (SwaggerPetstoreBackend t0)’
                with actual type ‘SwaggerPetstoreBackend SwaggerPetstoreClient’
    The function ‘createSwaggerPetstoreClient’
    is applied to one argument,
    but its type ‘SwaggerPetstoreBackend SwaggerPetstoreClient’
    has none
    In a stmt of a 'do' block:
      SwaggerPetstoreBackend {..} <- createSwaggerPetstoreClient
                                       (ServerConfig "localhost" 8080)
    In the expression:
      do { SwaggerPetstoreBackend {..} <- createSwaggerPetstoreClient
                                            (ServerConfig "localhost" 8080);
           return () }

[wing328]

When I run stack install with the latest master, I didn't get the error. Here is what I got:

haskell-servant|master⚡ ⇒ stack install
swagger-petstore-0.1.0.0: build (lib)
Preprocessing library swagger-petstore-0.1.0.0...
[2 of 2] Compiling SwaggerPetstore.API ( lib/SwaggerPetstore/API.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/SwaggerPetstore/API.o )
In-place registering swagger-petstore-0.1.0.0...
swagger-petstore-0.1.0.0: copy/register
Installing library in
/Users/williamcheng/Code/jan2017/swagger-codegen/samples/server/petstore/haskell-servant/.stack-work/install/x86_64-osx/lts-5.11/7.10.3/lib/x86_64-osx-ghc-7.10.3/swagger-petstore-0.1.0.0-IxSHpn14xIc0AqRoIN1bwh
Registering swagger-petstore-0.1.0.0...

[mandrean]

@wing328 Sorry, forgot the last step to reproduce. Updated initial post now.

This issue isn't about stack install failing, that was fixed recently in #5097 and merged to master.

This issue is about actually using the generated client/server library in your code, and the README.md example for doing that is broken.

[wing328]

@mandrean thanks for clarifying.

After the fix, we should leverage Travis CI to test the Haskell client/server for Petstore.

Ref: https://docs.haskellstack.org/en/stable/travis_ci/

cc @algas