that is a very basic implementation of Hackmd (codimd now) but in Purescript, see current page of corpus Node: you can edit and try (purescript).

Basic idea is having the capability to literally edit the text of the page, and see the result on the right. Data is either stored locally (kind of global state) or remote (in that case, in Json in the current Node).

Idea more generic: enable the tuning of parameters of function(s), configuration could be done in a kind of Dhall editor (instead of Purescript? Just an idea).