[jolmg]

> Interestingly this is exactly what I have been wishing was standard practice for a few years now!

You mean that when you call e.g. `tmux` you want to be forced to call it as something like `tmux -e HOME=... -e TERM=... -e DISPLAY=... -e USER=... ...`, and likewise for basically all other programs?

> I admit my years of experience with Haskell may have coloured this opinion.

Reader in Haskell helps prevent having to do that similar to environment variables or dynamic scoping, and is really, really common to use it as such instead of having to pass arguments around, so...

[dllthomas]

> Reader in Haskell helps prevent having to do that similar to environment variables or dynamic scoping

Reader in Haskell addresses some of the same concerns, but it differs in important ways. Reader is statically determined, Reader is clearly scoped to particular parts of your program (you can see whether a given function's behavior might depend on a value from a Reader in a way that's not visible with dynamic scope or environment variables), and Reader forces you to have set everything you might access. You could work around that last by making it a `Reader (Map String Dynamic)` or something, but that's not common in Haskell.

I make no claim, here, that these are obviously the right decisions - but they seem to provide enough differentiation that someone could rationally prefer one or the other.

[tome]

On the command line, i.e. a human interface, I'd be willing to soften my stance a bit but any time a program calls another program, yes, I would like it to be explicit about the parameters it accepts.

> Reader in Haskell helps prevent having to do that similar to environment variables or dynamic scoping

I would be happy with an interface like Reader in Haskell but I don't see that it's much like dynamic scope. The subject has been explored a few times in this discussion.