Suggestions for Short Examples Contrasting Functional Programming Languages
Project Euler has nice problems for showcasing the core of a programming language.
An important part of a programming language are user defined (container) data structures. Bread and butter containers include random access arrays, bidirectional lists, hash tables, and search trees. You may take the implementations from standard libraries of the languages to get interesting real world programs for you comparisons.
A strong point of functional programming languages is that they allow modular reuse of standard algorithms. The C++ stl header algorithm provides a nice collection of those reusable standard algorithms.