In this position paper, I present work we have conducted around the goals of making software malleable. Malleable software is software that a computer operator can appropriate and adapt to suit their own situated, idiosyncratic needs in ways not explicitly envisioned by the software designer. I describe past work in this space conducted with a variety of collaborators and students, as well as historical influences in this space. I conclude with a hint at a direction we are currently exploring in which computation is embedded in composable substrates rather than articulated through code.