From 71e1b2cbdc6656d59b180f70176b04efa0b9134a Mon Sep 17 00:00:00 2001
From: Kacper Donat <kadet1090@gmail.com>
Date: Wed, 28 Oct 2026 09:56:11 +0100
Subject: [PATCH] keep currying when compiling curried closures

---
 src/Utils/index.php   |  7 ++++++-
 tests/CompileTest.php | 17 +++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/Utils/index.php b/src/Utils/index.php
index b7ee398..aca3902 100644
--- a/src/Utils/index.php
+++ b/src/Utils/index.php
@@ -71,6 +71,9 @@ function memoize(callable $callable)
  * Flattens a callable into a plain closure. Compilable objects (decorators, pipelines, predicates) are compiled, so
  * calling the result does not go through them, also when given as a closure of their `__invoke` (e.g. `$pipe(...)`);
  * any other callable is converted with closure().
+ *
+ * A closure of a curried function's `__invoke` (`$curried(...)`) is kept as it is, so it keeps currying; the compiled
+ * curried function itself calls its target and does not curry further.
  */
 function compile(callable $callable): \Closure
 {
@@ -78,7 +81,9 @@ function compile(callable $callable): \Closure
         $reflection = new \ReflectionFunction($callable);
         $bound      = $reflection->getClosureThis();
 
-        return $bound instanceof Compilable && $reflection->getName() === '__invoke' ? $bound->compile() : $callable;
+        return $bound instanceof Compilable && !$bound instanceof CurriedFunction && $reflection->getName() === '__invoke'
+            ? $bound->compile()
+            : $callable;
     }
 
     return $callable instanceof Compilable ? $callable->compile() : closure($callable);
diff --git a/tests/CompileTest.php b/tests/CompileTest.php
index 81345ad..d9b159a 100644
--- a/tests/CompileTest.php
+++ b/tests/CompileTest.php
@@ -243,6 +243,23 @@ class CompileTest extends \PHPUnit\Framework\TestCase
         $this->assertSame($pipeline('a')('b'), f\compile($pipeline)('a')('b'));
     }
 
+    public function testCompiledClosureOfCurriedKeepsCurrying()
+    {
+        $curried = f\curry(fn ($a, $b) => "$a$b");
+
+        $this->assertSame('ab', f\compile($curried(...))('a')('b'));
+        $this->assertSame('ab', f\compile($curried(...))('a', 'b'));
+    }
+
+    public function testCompiledPipelineOfCurriedClosureKeepsCurrying()
+    {
+        $curried  = f\curry(fn ($a, $b) => "$a$b");
+        $pipeline = f\pipe(strtoupper(...), $curried(...));
+
+        $this->assertSame($pipeline('a')('b'), f\compile($pipeline)('a')('b'));
+        $this->assertSame('ab', f\compile(f\pipe($curried(...), fn ($rest) => $rest('b')))('a'));
+    }
+
     public function testCompileUnwrapsClosureOfCompilable()
     {
         $spy = new class(strtoupper(...)) extends FunctionPipeline {