lude

commit 3ec2498811182f8374267dc14cda113346fb6093
parent 79de4f2c7452ec562e8f5b54be650e44fc764fc8
Author: Robert Russell <robert@rr3.xyz>
Date:   Sat, 19 Sep 2026 15:46:51 -0700

Function: add fork (phi combinator)

Diffstat:
M
src/Lude.hs
 | 
2
+-
M
src/Lude/Function.hs
 | 
11
+++++++++--

2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/src/Lude.hs b/src/Lude.hs
@@ -7,7 +7,7 @@ import Lude.Bool as X
 import Lude.Constraint as X
 import Lude.Equivalence as X
 import Lude.Error as X
-import Lude.Function as X hiding ((.))
+import Lude.Function as X
 import Lude.Haskell as X
 import Lude.IO as X
 import Lude.List as X
diff --git a/src/Lude/Function.hs b/src/Lude/Function.hs
@@ -7,8 +7,9 @@ module Lude.Function (
     const,
     flip,
     on,
+    fork,
     compose00,
-    (.),
+    -- (.),
     compose01,
     (.*),
     compose10,
@@ -26,7 +27,7 @@ import Lude.Haskell
 
 -- TODO: How should we deal with the (.) naming conflict with category?
 
--- TODO: Repr-generic S and Phi combinators?
+-- TODO: Repr-generic S combinators?
 
 --------------------------------------------------------------------------------
 
@@ -58,6 +59,12 @@ on
 on f g = lam2# \x y -> app2# f (app# g x) (app# g y)
 {-# INLINE on #-}
 
+fork
+    :: forall {r :: Repr} (a :: Type @r) {s :: Repr} (b :: Type @s) {t :: Repr} (c :: Type @t) {u :: Repr} (d :: Type @u)
+     . (Functional# r, Functional# s, Functional# t) => (b -> c -> d) -> (a -> b) -> (a -> c) -> (a -> d)
+fork f g h = lam# \x -> app2# f (app# g x) (app# h x)
+{-# INLINE fork #-}
+
 --------------------------------------------------------------------------------
 -- Composition