Simple, Composable Pieces is practically the whole ethos of both Unix and Functional Programmers, and they both converged on the same basic flow model: Pipeline

Simple, Composable Pieces is practically the whole ethos of both Unix and Functional Programmers, and they both converged on the same basic flow model: Pipelines with minimal side-effects. This naturally leads to a sequential concurrency, which seems to be easy for humans to reason about: Data flows through the pipeline, different parts of the pipeline can all be active at once, and nobody loses track. It doesn't solve absolutely every possible problem, but the right group of pieces (utility programs, functions) will solve a surprising number of them without much trouble.