Add weeder

Makefile

@@ -189,6 +189,11 @@ validate-via-docker-8.10.1:
 validate-via-docker-old:
 	docker build -t cabal-validate -f .docker/validate-old.dockerfile .
 
+# Weeder
+weeder :
+	cabal build all --project-file=cabal.project.weeder
+	weeder | less
+
 # tags
 .PHONY : tags
 tags :

cabal.project.weeder

+-- project file for weeder. Only Cabal and cabal install
+-- install weeder with
+--
+--     cabal install -w ghc-8.8.3 weeder
+--
+
+packages: Cabal/
+packages: cabal-install/
+tests: False
+
+with-compiler: ghc-8.8.3
+
+package *
+  ghc-options: -fwrite-ide-info

weeder.dhall

+{ roots = [ "^Main.main$" ], type-class-roots = True }