Draw blank screen with render pipeline!

The linear types are finally paying off (GREAT!) in handling references
to pipelines and such, and guaranteeing they are freed exactly once. I'm
getting no runtime errors at all :)

ghengin-core/ghengin-core/Ghengin/Core/Render/Packet.hs

@@ -96,7 +96,7 @@ described in bytes.
  -}
 
 -- TODO: Each render packet is then assigned with an ID and sorted in an optimal draw order.
--- Alternative: Meshes, Materials and RenderPipelines have an Ord instance and we make a 3-layer map
+-- Alternative: Meshes, Materials and RenderPipelines have an Ord instance and we make a 3-layer map <-- this is what we've done...
 
 -- | Render packet wrapper that creates the key identifier.
 -- {-# DEPRECATED renderPacket "FIXME: Compute materialUID" #-}

ghengin-core/ghengin-core/Ghengin/Core/Render/Queue.hs

@@ -72,6 +72,26 @@ instance Monoid (RenderQueue α) where
 -- fromList = foldr ((<>) . (`insert` mempty)) mempty :)
 -- {-# INLINE fromList #-}
 
+-- | ... We assume there are no two pipelines with the exact same shaders
+newtype PipelineKey π p = UnsafePipelineKey TypeRep
+
+-- | Inserts a pipeline in a render queue, and returns a pipeline key indexing
+-- into that render queue.
+insertPipeline :: forall π p α. Typeable π
+               => RenderPipeline π p
+                ⊸ RenderQueue α
+                ⊸ (RenderQueue α, Ur (PipelineKey π p))
+insertPipeline 
+  -- Map.insert isn't linear still, so...
+  = Unsafe.toLinear2 \pipeline (RenderQueue q) ->
+    let pkey = typeRep (Proxy @π)
+        rq'  = RenderQueue $
+                 M.insertWith
+                    (\_ _ -> error "Inserting a duplicate pipeline??")
+                    pkey
+                    (Some2 pipeline, M.empty)
+                    q
+     in (rq', Ur $ UnsafePipelineKey pkey)
 
 -- TODO: Rather, to create a renderpacket we need a render queue, since we
 -- extract the render key from the render queue and the references into the

ghengin-games/planets-core/Main.hs

@@ -124,13 +124,14 @@ main = do
     pipeline            <- (makeMainPipeline ↑)
     (p1mesh, Ur minmax) <- newPlanetMesh defaultPlanetSettings
     (pmat, pipeline)    <- newPlanetMaterial minmax tex pipeline
+    (rq, Ur pkey)       <- pure (insertPipeline pipeline LMon.mempty)
 
-    rq <- gameLoop currTime LMon.mempty
+    rq' <- gameLoop currTime rq
 
     (freeMaterial pmat ↑)
     (freeMesh p1mesh ↑)
-    (freeRenderQueue rq ↑)
-    (destroyRenderPipeline pipeline ↑)
+    (freeRenderQueue rq' ↑)
+    -- (destroyRenderPipeline pipeline ↑)
 
     return (Ur ())