From ba5a31c976f80421464af1af8d6ab1e2a154cd83 Mon Sep 17 00:00:00 2001
From: Mikolaj Konarski <mikolaj.konarski@funktory.com>
Date: Tue, 2 Dec 2025 05:38:41 +0100
Subject: Define mgeneratePrim as a fast special case variant

---
 src/Data/Array/Nested/Ranked.hs | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'src/Data/Array/Nested/Ranked.hs')

diff --git a/src/Data/Array/Nested/Ranked.hs b/src/Data/Array/Nested/Ranked.hs
index bf35cc4..9504247 100644
--- a/src/Data/Array/Nested/Ranked.hs
+++ b/src/Data/Array/Nested/Ranked.hs
@@ -69,6 +69,15 @@ rgenerate sh f
   , Refl <- lemRankReplicate sn
   = Ranked (mgenerate (shxFromShR sh) (f . ixrFromIxX))
 
+-- TODO: this would be shorter and faster written with rfromVector,
+-- but unfortunately we don't have ixrFromLinear
+rgeneratePrim :: forall n a. PrimElt a => IShR n -> (IIxR n -> a) -> Ranked n a
+rgeneratePrim sh f
+  | sn@SNat <- shrRank sh
+  , Dict <- lemKnownReplicate sn
+  , Refl <- lemRankReplicate sn
+  = Ranked (mgeneratePrim (shxFromShR sh) (f . ixrFromIxX))
+
 -- | See the documentation of 'mlift'.
 rlift :: forall n1 n2 a. Elt a
       => SNat n2
-- 
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