Chemlambda specifies local asynchronous and reversible rewrite rules simultaneously analogous to both computation and organic synthesis. Here classic computations are visualized in their "molecular" form using d3's force layout for rendering only. github 
quotes
Metabolism, as the process which consists into the exchange with the medium and the replenishment of the constitutive atoms, maintaining the overall structure of the organism.
Chemlambda is a graph rewriting system derived from graphic lambda calculus which can be seen as a simple model of chemical or biological computing.
Molecules, i.e. the chemlambda graphs, appear as .mol files, it is important to understand the notation. The program works with the mol files and produces a html file which contains the visualisation of the execution of the algorithm from the main script.
The visualisation is not needed for the chemlambda formalism, but is useful for your understanding of what happens. Therefore chemlambda is not a visualiser for lambda calculus, but it can be used for this, in particular.
.