purescript · garyb · Sep 23, 2017 · Jul 4, 2017 · Jul 4, 2017 · Jul 4, 2017
diff --git a/examples/failing/2197-shouldFail.purs b/examples/failing/2197-shouldFail.purs
@@ -0,0 +1,10 @@
+-- @shouldFailWith ScopeConflict
+module Main where
+
+import Prim as P
+import Prim (Number)
+
+type Number = P.Number
+
+z :: Number
+z = 0.0
diff --git a/examples/failing/2197-shouldFail2.purs b/examples/failing/2197-shouldFail2.purs
@@ -0,0 +1,7 @@
+-- @shouldFailWith UnknownName
+module Main where
+
+import Prim (Boolean)
+
+z :: Number
+z = 0.0
diff --git a/examples/passing/2197-1.purs b/examples/passing/2197-1.purs
@@ -0,0 +1,12 @@
+module Main where
+
+import Control.Monad.Eff.Console
+import Prim as P
+
+type Number = P.Number
+type Test = {}
+
+z :: Number
+z = 0.0
+
+main = log "Done"
diff --git a/examples/passing/2197-2.purs b/examples/passing/2197-2.purs
@@ -0,0 +1,11 @@
+module Main where
+
+import Control.Monad.Eff.Console
+import Prim (Int)
+
+type Number = Int
+
+z :: Number
+z = 0
+
+main = log "Done"
diff --git a/src/Language/PureScript/AST/Declarations.hs b/src/Language/PureScript/AST/Declarations.hs
@@ -229,12 +229,19 @@ getModuleSourceSpan (Module ss _ _ _ _) = ss
 -- |
 -- Add an import declaration for a module if it does not already explicitly import it.
 --
+-- Will not import an unqualified module if that module has already been imported qualified.
+-- (See #2197)
+--
 addDefaultImport :: Qualified ModuleName -> Module -> Module
 addDefaultImport (Qualified toImportAs toImport) m@(Module ss coms mn decls exps) =
   if isExistingImport `any` decls || mn == toImport then m
   else Module ss coms mn (ImportDeclaration (ss, []) toImport Implicit toImportAs : decls) exps
   where
-  isExistingImport (ImportDeclaration _ mn' _ as') | mn' == toImport && as' == toImportAs = True
+  isExistingImport (ImportDeclaration _ mn' _ as')
+    | mn' == toImport =
+        case toImportAs of
+          Nothing -> True
+          _ -> as' == toImportAs
   isExistingImport _ = False
 
 -- | Adds import declarations to a module for an implicit Prim import and Prim
@@ -244,8 +251,8 @@ importPrim =
   let
     primModName = ModuleName [ProperName C.prim]
   in
-    addDefaultImport (Qualified Nothing primModName)
-      . addDefaultImport (Qualified (Just primModName) primModName)
+    addDefaultImport (Qualified (Just primModName) primModName)
+      . addDefaultImport (Qualified Nothing primModName)
 
 -- |
 -- An item in a list of explicit imports or exports

diff --git a/src/Language/PureScript/Docs/Prim.hs b/src/Language/PureScript/Docs/Prim.hs
@@ -12,7 +12,7 @@ import qualified Language.PureScript as P
 primDocsModule :: Module
 primDocsModule = Module
   { modName = P.moduleNameFromString "Prim"
-  , modComments = Just "The Prim module is embedded in the PureScript compiler in order to provide compiler support for certain types &mdash; for example, value literals, or syntax sugar."
+  , modComments = Just "The Prim module is embedded in the PureScript compiler in order to provide compiler support for certain types &mdash; for example, value literals, or syntax sugar. It is implicitly imported unqualified in every module except those that list it as a qualified import."
   , modDeclarations =
       [ function
       , array