The ability to reproduce an experiment is fundamental in computer science. Existing approaches focus on repeatability, but this is only the first step to repro-ducibility: Continuing a scientific work from a previous experiment requires to be able to modify it. This ability is called reproducibility with Variation. In this contribution, we show that capturing the environment of execution is necessary but not sufficient ; we also need the environment of development. The variation also implies that those environments are subject to evolution, so the whole software development lifecycle needs to be considered. To take into account these evolutions, software environments need to be clearly defined, reconstructible with variation, and easy to share. We propose to leverage functional package managers to achieve this goal.