feat(logic): add functional functions

x/logic/util/func.go

@@ -0,0 +1,22 @@
+package util
+
+import "github.com/samber/lo"
+
+// WhitelistBlacklistMatches returns a function that matches the given item according to the given whitelist and
+// blacklist returning true if the item matches the whitelist and does not match the blacklist, and false otherwise.
+// Note that if the whitelist is empty, the item is considered to match the whitelist.
+func WhitelistBlacklistMatches[T any](whitelist []T, blacklist []T, predicate func(item T) func(b T) bool) func(T) bool {
+	return func(item T) bool {
+		matches := predicate(item)
+		return ((len(whitelist) == 0) || lo.ContainsBy(whitelist, matches)) && !lo.ContainsBy(blacklist, matches)
+	}
+}
+
+// Indexed returns a function that applies the given function to the given item and returns the result.
+// It's a convenience function to be used with lo.Map which transforms a predicate function into a mapper function
+// by adding an index argument (which is ignored).
+func Indexed[T any, U any](f func(t T) U) func(T, int) U {
+	return func(t T, _ int) U {
+		return f(t)
+	}
+}