From 19d1236d54002dd4b14cdb7e76970b8475ed013a Mon Sep 17 00:00:00 2001
From: ilkecan <ilkecan@protonmail.com>
Date: Wed, 7 Sep 2022 00:52:51 +0000
Subject: [PATCH] each{,Default}System: accept binary functions

Closes: #78
---
 README.md   | 8 ++++++++
 default.nix | 9 ++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index e2ac15e..46ca7dc 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,14 @@ eachSystem allSystems (system: { hello = 42; })
 }
 ```
 
+If you pass a function rather than an attribute set after the `system` argument,
+it will receive as its argument the final attribute set. For example: 
+```nix
+eachSystem [ system.x86_64-linux ] (system: self: { a = 2; b = self.a + 3; })
+```
+`self` is not that useful in this case, as it can be replaced with the `rec`
+keyword but there can be situations where it is preferred.
+
 ### `eachDefaultSystem -> (<system> -> attrs)`
 
 `eachSystem` pre-populated with `defaultSystems`.
diff --git a/default.nix b/default.nix
index 8c2c729..8cf4892 100644
--- a/default.nix
+++ b/default.nix
@@ -125,7 +125,14 @@ let
       # Merge together the outputs for all systems.
       op = attrs: system:
         let
-          ret = f system;
+          ret =
+            let
+              retOrFunc = f system;
+            in
+            if builtins.isFunction retOrFunc
+              then retOrFunc ret
+              else retOrFunc;
+
           op = attrs: key:
             let
               appendSystem = key: system: ret: