That version (and the one in the article) are somewhat confusing to parse and detract from the point of the article. This seems more "Pythonic": def looku

That version (and the one in the article) are somewhat confusing to parse and detract from the point of the article. This seems more "Pythonic": def lookup(d, key): return Just(d[key]) if key in d else None def values_in(keys, d): values = [] for k in keys: x = lookup(d, k) if x: values.append(x.value) return values If you really want a one-liner, I think this is easier to understand: def values_in(keys, d): return [x.value for x in (lookup(d, k) for k in keys) if x]