Issue 33: Finished most aspects of the expression language (#38)

- Most aspects of scans and queries can now be represented using the expression language
- All constructs of the expression language can be used to evaluate items

internal/common/sliceutils/map.go

@@ -8,6 +8,19 @@ func Map[T, U any](ts []T, fn func(t T) U) []U {
 	return us
 }
 
+func MapWithError[T, U any](ts []T, fn func(t T) (U, error)) ([]U, error) {
+	us := make([]U, len(ts))
+
+	for i, t := range ts {
+		var err error
+		us[i], err = fn(t)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return us, nil
+}
+
 func Filter[T any](ts []T, fn func(t T) bool) []T {
 	us := make([]T, 0)
 	for _, t := range ts {