move: advanced funcs to functional programming

27-functional-programming/log-parser-exp/groupers.go

@@ -0,0 +1,21 @@
+package main
+
+// domainGrouper groups by domain.
+// but it keeps the other fields.
+// for example: it returns pages as well, but you shouldn't use them.
+// exercise: write a function that erases superfluous data.
+func domainGrouper(r result) string {
+	return r.domain
+}
+
+func pageGrouper(r result) string {
+	return r.domain + r.page
+}
+
+// you could have created a noopGrouper as well
+// but it's not necessary i think (map allocation)
+func noopGrouper(r result) string {
+	// with something like:
+	// return randomStrings()
+	return ""
+}