diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@
 
 ```bash
 cabal update
-cabal install --overwrite-policy=always phino-0.0.0.71
+cabal install --overwrite-policy=always phino-0.0.0.72
 phino --version
 ```
 
@@ -392,55 +392,55 @@
 === parse/phi ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      1419098.230 μs
-  avg:        141909.823 μs
-  min:        127594.959 μs
-  max:        173890.065 μs
-  std dev:    17203.851 μs
+  total:      1281818.631 μs
+  avg:        128181.863 μs
+  min:        115976.108 μs
+  max:        157716.092 μs
+  std dev:    17330.936 μs
 === parse/xmir ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      7668285.122 μs
-  avg:        766828.512 μs
-  min:        701875.873 μs
-  max:        834845.017 μs
-  std dev:    47941.411 μs
+  total:      7703218.666 μs
+  avg:        770321.867 μs
+  min:        708375.007 μs
+  max:        835194.999 μs
+  std dev:    41016.808 μs
 === rewrite/normalize ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      419697.477 μs
-  avg:        41969.748 μs
-  min:        39760.750 μs
-  max:        44430.602 μs
-  std dev:    1609.092 μs
+  total:      546667.979 μs
+  avg:        54666.798 μs
+  min:        47131.404 μs
+  max:        61636.208 μs
+  std dev:    4936.214 μs
 === print/sweet/multiline ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      4102201.200 μs
-  avg:        410220.120 μs
-  min:        392265.453 μs
-  max:        432892.821 μs
-  std dev:    12013.486 μs
+  total:      4661151.196 μs
+  avg:        466115.120 μs
+  min:        458816.744 μs
+  max:        478741.573 μs
+  std dev:    6479.319 μs
 === print/sweet/flat ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      3992227.126 μs
-  avg:        399222.713 μs
-  min:        381853.621 μs
-  max:        416304.939 μs
-  std dev:    11016.036 μs
+  total:      4649931.918 μs
+  avg:        464993.192 μs
+  min:        426197.450 μs
+  max:        489664.247 μs
+  std dev:    25327.503 μs
 === print/salty/multiline ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      13721988.418 μs
-  avg:        1372198.842 μs
-  min:        1332480.796 μs
-  max:        1420431.251 μs
-  std dev:    28529.557 μs
+  total:      14136736.780 μs
+  avg:        1413673.678 μs
+  min:        1382452.302 μs
+  max:        1433158.708 μs
+  std dev:    16632.911 μs
 ```
 
 The results were calculated in [this GHA job][benchmark-gha]
-on 2026-06-01 at 19:59,
+on 2026-06-02 at 03:47,
 on Linux with 4 CPUs.
 
 <!-- benchmark_end -->
@@ -476,4 +476,4 @@
 [jna]: https://github.com/java-native-access/jna
 [jna-native]: https://github.com/java-native-access/jna/blob/master/src/com/sun/jna/Native.java
 [jeo]: https://github.com/objectionary/jeo-maven-plugin
-[benchmark-gha]: https://github.com/objectionary/phino/actions/runs/26778383106
+[benchmark-gha]: https://github.com/objectionary/phino/actions/runs/26796987208
diff --git a/phino.cabal b/phino.cabal
--- a/phino.cabal
+++ b/phino.cabal
@@ -1,6 +1,6 @@
 cabal-version: 3.0
 name: phino
-version: 0.0.0.72
+version: 0.0.0.73
 license: MIT
 synopsis: Command-Line Manipulator of 𝜑-Calculus Expressions
 description: Please see the README on GitHub at <https://github.com/objectionary/phino#readme>
diff --git a/src/Yaml.hs b/src/Yaml.hs
--- a/src/Yaml.hs
+++ b/src/Yaml.hs
@@ -120,7 +120,15 @@
       ]
 
 instance FromJSON Extra where
-  parseJSON = genericParseJSON defaultOptions
+  parseJSON =
+    withObject
+      "Extra"
+      ( \o ->
+          Extra
+            <$> o .: "meta"
+            <*> o .: "function"
+            <*> o .:? "args" .!= []
+      )
 
 instance FromJSON Rule where
   parseJSON =