Yash: Posix-compliant shell with fish-style predictive completion and more

From the project website:

> Yash is intended to be the most POSIX-compliant shell in the world while supporting features for daily interactive and scripting use. Notable features are:

   * Global aliases

   * Arrays

   * Socket redirection, pipeline redirection, and process redirection

   * Brace expansion and extended globbing

   * Fractional numbers in arithmetic expansion

   * Prompt command and command-not-found handler

   * Command line completion with predefined completion scripts for more than 100 commands

   * Command line prediction based on command history

I'm particularly taken with it's support for configuring the relevant keyboard commands, with strong support for both Emacs and Vi bindings.

It also uses much less RAM than many other shells with similar interactive features, to the extent that matters to folks these days.