We could also leave this as an add-on command. What might be some arguments against making it a builtin ?

• I hope in future we can speed up hledger more, perhaps with caching, which might reduce the benefit of this command a bit. It might be a temporary fix, not long term need.

• We might feel concerned about scope creep, adding complexity and dev distractions, and inventing our own custom scripting language.

Arguments for:

• Built in commands get used and improved, addons don't

• We might find some cool enhancement ideas

• Optimisation might not happen, and even if it does there's always sufficiently large data / slow machines to appreciate a speed up

• Avoiding wasted work, eg when generating scripted reports, is simply good economy of resources

• Ledger and Beancount both provide such a REPL, for similar reasons presumably, though I don't hear these REPLs discussed.

• This is extending a capability already present in hledger-ui and hledger-web, to the CLI.

• It's a step towards better support for complex/compound reports.