add support for deriving strategies

Author: raichoo

indent/haskell.vim

@@ -318,7 +318,7 @@ function! GetHaskellIndent()
 
   " newtype Foo = Foo
   " >>deriving
-  if l:prevline =~ '\C\s*\<\(newtype\|data\)\>[^{]\+' && l:line =~ '\C^\s*\<deriving\>'
+  if l:prevline =~ '\C^\s*\<\(newtype\|data\)\>[^{]\+' && l:line =~ '\C^\s*\<deriving\>'
     return match(l:prevline, '\S') + &shiftwidth
   endif
 

syntax/haskell.vim

@@ -36,7 +36,8 @@ syn match haskellTypeSig
   \ haskellParens
 syn keyword haskellWhere where
 syn keyword haskellLet let
-syn keyword haskellDeclKeyword module class instance newtype deriving in
+syn match HaskellDerive "\<deriving\>\s\+\<\(anyclass\|instance\|newtype\|stock\)\?"
+syn keyword haskellDeclKeyword module class instance newtype in
 syn match haskellDecl "\<\(type\|data\)\>\s\+\(\<family\>\)\?"
 syn keyword haskellDefault default
 syn keyword haskellImportKeywords import qualified safe as hiding contained
@@ -159,11 +160,13 @@ highlight def link haskellType Type
 highlight def link haskellImportKeywords Include
 if get(g:, 'haskell_classic_highlighting', 0)
   highlight def link haskellDeclKeyword Keyword
+  highlight def link HaskellDerive Keyword
   highlight def link haskellDecl Keyword
   highlight def link haskellWhere Keyword
   highlight def link haskellLet Keyword
 else
   highlight def link haskellDeclKeyword Structure
+  highlight def link HaskellDerive Structure
   highlight def link haskellDecl Structure
   highlight def link haskellWhere Structure
   highlight def link haskellLet Structure