dependency ladder example

slides/makefiles/dependency_ladder/makes/cows

@@ -0,0 +1,10 @@
+cows = $(patsubst Forts/fortune_%.md,Cows/cow-%.txt,$(wildcard Forts/fortune_*.md))
+
+$(cows): Cows/cow-%.txt: Forts/fortune_%.md
+	@mkdir -p $(@D)
+	cat $< | cowsay > $@
+
+progs += forts
+progs += $(cows)
+dross += Cows/
+