Different with-http CPP check; fix remote imports in GHCJS (#1330)

Completes the changes in #1311

dhall/dhall.cabal

@@ -429,6 +429,9 @@ Library
       Build-Depends: semigroups == 0.18.*
       Build-Depends: transformers == 0.4.2.*
       Build-Depends: fail == 4.9.*
+    if flag(with-http)
+      CPP-Options:
+        -DWITH_HTTP
     if impl(ghcjs)
       Hs-Source-Dirs: ghcjs-src
       Build-Depends:

dhall/doctest/Main.hs

@@ -25,7 +25,8 @@ main = do
         writeFile "file1" "./file2"
 
         Test.DocTest.doctest
-            [ "--fast"
+            [ "-DWITH_HTTP"
+            , "--fast"
             , "-i" <> (prefix </> "src")
             , "-i" <> (prefix </> "ghc-src")
             , prefix </> "src/Dhall.hs"

dhall/ghc-src/Dhall/Import/HTTP.hs

@@ -258,12 +258,10 @@ corsCompliant _ _ _ = return ()
 
 type HTTPHeader = Network.HTTP.Types.Header
 
-fetchFromHttpUrl
-    :: Manager
-    -> URL
-    -> Maybe [HTTPHeader]
-    -> StateT Status IO Text.Text
-fetchFromHttpUrl manager childURL mheaders = do
+fetchFromHttpUrl :: URL -> Maybe [HTTPHeader] -> StateT Status IO Text.Text
+fetchFromHttpUrl childURL mheaders = do
+    manager <- liftIO $ newManager
+
     let childURLString = Text.unpack (renderURL childURL)
 
     request <- liftIO (HTTP.parseUrlThrow childURLString)

dhall/ghcjs-src/Dhall/Import/HTTP.hs

@@ -17,11 +17,10 @@ import Dhall.URL (renderURL)
 import Dhall.Import.Types
 
 fetchFromHttpUrl
-    :: a
-    -> URL
+    :: URL
     -> Maybe [(CI ByteString, ByteString)]
     -> StateT Status IO Text.Text
-fetchFromHttpUrl _ childURL Nothing = do
+fetchFromHttpUrl childURL Nothing = do
     let childURLText = renderURL childURL
 
     let childURLString = Text.unpack childURLText
@@ -35,5 +34,5 @@ fetchFromHttpUrl _ childURL Nothing = do
         _   -> fail (childURLString <> " returned a non-200 status code: " <> show statusCode)
 
     return body
-fetchFromHttpUrl _ _ _ = do
+fetchFromHttpUrl _ _ = do
     fail "Dhall does not yet support custom headers when built using GHCJS"

dhall/src/Dhall/Import.hs

@@ -171,8 +171,7 @@ import Dhall.Core
     , bindingExprs
     , chunkExprs
     )
-#ifdef MIN_VERSION_http_client
-import Network.HTTP.Client (Manager)
+#ifdef WITH_HTTP
 import Dhall.Import.HTTP hiding (HTTPHeader)
 #endif
 import Dhall.Import.Types
@@ -703,7 +702,7 @@ fetchFresh Missing = throwM (MissingImports [])
 
 
 fetchRemote :: URL -> StateT Status IO Data.Text.Text
-#ifndef MIN_VERSION_http_client
+#ifndef WITH_HTTP
 fetchRemote (url@URL { headers = maybeHeadersExpression }) = do
     let maybeHeaders = fmap toHeaders maybeHeadersExpression
     let urlString = Text.unpack (Dhall.Core.pretty url)
@@ -711,14 +710,13 @@ fetchRemote (url@URL { headers = maybeHeadersExpression }) = do
     throwMissingImport (Imported _stack (CannotImportHTTPURL urlString maybeHeaders))
 #else
 fetchRemote url = do
-    manager <- liftIO $ newManager
-    zoom remote (State.put (fetchFromHTTP manager))
-    fetchFromHTTP manager url
+    zoom remote (State.put fetchFromHTTP)
+    fetchFromHTTP url
   where
-    fetchFromHTTP :: Manager -> URL -> StateT Status IO Data.Text.Text
-    fetchFromHTTP manager (url'@URL { headers = maybeHeadersExpression }) = do
+    fetchFromHTTP :: URL -> StateT Status IO Data.Text.Text
+    fetchFromHTTP (url'@URL { headers = maybeHeadersExpression }) = do
         let maybeHeaders = fmap toHeaders maybeHeadersExpression
-        fetchFromHttpUrl manager url' maybeHeaders
+        fetchFromHttpUrl url' maybeHeaders
 #endif
 
 -- | Given a well-typed (of type `List { header : Text, value Text }` or