I see. I'm a big fan of DSLs, but the internal vs. external distinction is not something I've seen articulated before.
For now, I'm treating Sheet Markup as an external DSL, which can be embedded in a Markdown document using a fenced code block. But there are certainly benefits (and costs) to developing an internal DSL for spreadsheets along the lines of what you're suggesting.
For now, I'm treating Sheet Markup as an external DSL, which can be embedded in a Markdown document using a fenced code block. But there are certainly benefits (and costs) to developing an internal DSL for spreadsheets along the lines of what you're suggesting.