diff --git a/config/models b/config/models
index d14d0d4..4035f5f 100644
--- a/config/models
+++ b/config/models
@@ -86,6 +86,12 @@ ProjectRole
 
     UniqueProjectRole sharer ident
 
+ProjectRoleInherit
+    parent ProjectRoleId
+    child  ProjectRoleId
+
+    UniqueProjectRoleInherit parent child
+
 ProjectAccess
     role ProjectRoleId
     op   ProjectOperation
@@ -99,12 +105,6 @@ ProjectCollab
 
     UniqueProjectCollab project person
 
-ProjectRoleInherit
-    parent ProjectRoleId
-    child  ProjectRoleId
-
-    UniqueProjectRoleInherit parent child
-
 -------------------------------------------------------------------------------
 -- Projects
 -------------------------------------------------------------------------------
diff --git a/src/Vervis/Model.hs b/src/Vervis/Model.hs
index 5e04d66..255e114 100644
--- a/src/Vervis/Model.hs
+++ b/src/Vervis/Model.hs
@@ -43,3 +43,13 @@ instance HashDBUser Person where
 instance Hashable MessageId where
     hashWithSalt salt = hashWithSalt salt . fromSqlKey
     hash = hash . fromSqlKey
+
+-- "Vervis.Role" uses a 'HashMap' where the key type is 'RepoRoleId'
+instance Hashable RepoRoleId where
+    hashWithSalt salt = hashWithSalt salt . fromSqlKey
+    hash = hash . fromSqlKey
+
+-- "Vervis.Role" uses a 'HashMap' where the key type is 'ProjectRoleId'
+instance Hashable ProjectRoleId where
+    hashWithSalt salt = hashWithSalt salt . fromSqlKey
+    hash = hash . fromSqlKey
diff --git a/src/Vervis/Role.hs b/src/Vervis/Role.hs
new file mode 100644
index 0000000..b08dfc6
--- /dev/null
+++ b/src/Vervis/Role.hs
@@ -0,0 +1,90 @@
+{- This file is part of Vervis.
+ -
+ - Written in 2016 by fr33domlover <fr33domlover@riseup.net>.
+ -
+ - ♡ Copying is an act of love. Please copy, reuse and share.
+ -
+ - The author(s) have dedicated all copyright and related and neighboring
+ - rights to this software to the public domain worldwide. This software is
+ - distributed without any warranty.
+ -
+ - You should have received a copy of the CC0 Public Domain Dedication along
+ - with this software. If not, see
+ - <http://creativecommons.org/publicdomain/zero/1.0/>.
+ -}
+
+module Vervis.Role
+    ( getRepoRoleGraph
+    , getProjectRoleGraph
+    )
+where
+
+import Prelude
+
+import Control.Arrow (second, (&&&), (***))
+import Data.Graph.Inductive.Graph (mkGraph)
+import Data.Graph.Inductive.PatriciaTree (Gr)
+import Data.Tuple (swap)
+import Database.Esqueleto
+import Yesod.Persist.Core (runDB)
+
+import qualified Data.HashMap.Lazy as M (fromList, lookup)
+import qualified Database.Persist as P
+
+import Vervis.Foundation
+import Vervis.Model
+import Vervis.Model.Ident
+
+getRepoRoleGraph :: AppDB SharerId -> Handler (Gr RlIdent ())
+getRepoRoleGraph getsid = do
+    (roles, inhs) <- runDB $ do
+        sid <- getsid
+        rrs <- P.selectList [RepoRoleSharer P.==. sid] []
+        rrhs <- select $ from $ \ (rr `InnerJoin` rrh) -> do
+            on $ rr ^. RepoRoleId ==. rrh ^. RepoRoleInheritParent
+            where_ $ rr ^. RepoRoleSharer ==. val sid
+            return rrh
+        return (rrs, rrhs)
+    let numbered = zip [1..] roles
+        nodes = map (second $ repoRoleIdent . entityVal) numbered
+        nodeMap = M.fromList $ map (swap . second entityKey) numbered
+        rridToNode rrid =
+            case M.lookup rrid nodeMap of
+                Nothing -> error "Role graph: Node not found in node map"
+                Just n  -> n
+        edges =
+            map
+                ( (\ (c, p) -> (c, p, ()))
+                . (rridToNode *** rridToNode)
+                . (repoRoleInheritChild &&& repoRoleInheritParent)
+                . entityVal
+                )
+                inhs
+    return $ mkGraph nodes edges
+
+getProjectRoleGraph :: AppDB SharerId -> Handler (Gr RlIdent ())
+getProjectRoleGraph getsid = do
+    (roles, inhs) <- runDB $ do
+        sid <- getsid
+        prs <- P.selectList [ProjectRoleSharer P.==. sid] []
+        prhs <- select $ from $ \ (pr `InnerJoin` prh) -> do
+            on $ pr ^. ProjectRoleId ==. prh ^. ProjectRoleInheritParent
+            where_ $ pr ^. ProjectRoleSharer ==. val sid
+            return prh
+        return (prs, prhs)
+    let numbered = zip [1..] roles
+        nodes = map (second $ projectRoleIdent . entityVal) numbered
+        nodeMap = M.fromList $ map (swap . second entityKey) numbered
+        pridToNode prid =
+            case M.lookup prid nodeMap of
+                Nothing -> error "Role graph: Node not found in node map"
+                Just n  -> n
+        edges =
+            map
+                ( (\ (c, p) -> (c, p, ()))
+                . (pridToNode *** pridToNode)
+                . (projectRoleInheritChild &&& projectRoleInheritParent)
+                . entityVal
+                )
+                inhs
+    return $ mkGraph nodes edges
diff --git a/vervis.cabal b/vervis.cabal
index d8d4f3e..ac256c3 100644
--- a/vervis.cabal
+++ b/vervis.cabal
@@ -135,6 +135,7 @@ library
                        Vervis.Query
                        Vervis.Readme
                        Vervis.Render
+                       Vervis.Role
                        Vervis.Settings
                        Vervis.Settings.StaticFiles
                        Vervis.SourceTree