Add --flags=optimize for cabal configure

hnix.cabal

@@ -2,7 +2,7 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: bd76dbaf4832c321feb19fe34a80e29c90cdbc150048dcee92038f96725c4f30
+-- hash: 16beb8d29116e6049b925d6727fb8e104c6722c162db8fa745bc2ec17724da47
 
 name:           hnix
 version:        0.5.0
@@ -25,6 +25,11 @@ source-repository head
   type: git
   location: https://github.com/jwiegley/hnix
 
+flag optimize
+  description: Enable all optimization flags
+  manual: True
+  default: False
+
 flag tracing
   description: Enable full debug tracing
   manual: True

package.yaml

@@ -33,8 +33,6 @@ dependencies:
 
 ghc-options:
   - -Wall
-  # - -fexpose-all-unfoldings
-  # - -O2
 
 flags:
   tracing:
@@ -42,6 +40,18 @@ flags:
     manual: True
     default: False
 
+  optimize:
+    description: Enable all optimization flags
+    manual: True
+    default: False
+
+when:
+  - condition: flag(optimize)
+    ghc-options:
+      - -fexpose-all-unfoldings
+      - -fspecialise-aggressively
+      - -O2
+
 when:
   - condition: flag(tracing)
     cpp-options: -DENABLE_TRACING=1