@mattly: ah good to hear, thanks

there's no built-in way of mapping over a the Left of an Either is there?

I have a mlet block where functions work on over small parts of a larger datastructure, so I'm able to nicely log at what stage do things go wrong, but I'd also like to include the larger datastructure into the map that my Left branch returns so that I can quickly run tests on the failure case

right now I'm doing: https://gist.github.com/luxbock/43834bb24d9b0a560229c7e24bcc3cd5

but it feels a bit ugly EDIT: just realized there's m/left-map, doh