This bit of the Guix documentation provides a better explanation of why monads are useful than I could give: The procedures that operate on the store descr

This bit of the Guix documentation provides a better explanation of why monads are useful than I could give: The procedures that operate on the store described in the previous sections all take an open connection to the build daemon as their first argument. Although the underlying model is functional, they either have side effects or depend on the current state of the store. The former is inconvenient: the connection to the build daemon has to be carried around in all those functions, making it impossible to compose functions that do not take that parameter with functions that do. The latter can be problematic: since store operations have side effects and/or depend on external state, they have to be properly sequenced. This is where the (guix monads) module comes in. This module provides a framework for working with monads, and a particularly useful monad for our uses, the store monad. Monads are a construct that allows two things: associating “context” with values (in our case, the context is the store), and building sequences of computations (here computations include accesses to the store.) Values in a monad—values that carry this additional context—are called monadic values; procedures that return such values are called monadic procedures. https://gnu.org/software/guix/manual/html_node/The-Store-Monad.html#The-Store-Monad https://gnu.org/software/guix/manual/html_node/The-Store-Mon...