Io's method_missing
coroutines in Io

Concurrency in Io
concurrency: actors in Io
Basic Facts in Prolog
fixing typo
Basic Inferences and Variables in Prolog
Filling in the Blanks in Prolog
Map Coloring in Prolog
Unification in Prolog, part 1
Recursion in Prolog
Unification part 2, lists and tuples
Lists and Math in Prolog
Lists in Prolog: Using Rules in Both Directions
concatenate lists in Prolog, step 1
concatenate lists in Prolog, step 2
concatenate lists in Prolog, step 3
concatenate lists in Prolog, final version