> a huge chunk of that (a couple 100KLOCs at least) is the Haskell compiler itself, which they've modified and consider a part of their codebase
Please don't talk about what you don't know. Standard Chartered's Haskell compiler is written completely from scratch and is not based on any existing compiler.
Sorry, that's what I'd heard (or I may have misinterpreted "a variant of Haskell" as "a variant of the Haskell compiler" all on my own); thank you for correcting me. So what you're saying is that biggest Haskell program isn't the Haskell compiler, but that the two biggest[1] Haskell programs are two completely different Haskell compilers.
(Also, while it has little to do with my point, I've also heard that the person behind SC's Haskell compiler is the one who'd written the first ever Haskell compiler, long before he started working for SC; is that true?)
[1]: Please don't take this too literally. In the two decades that have passed since Haskell was declared the language to end world hunger, someone may have written a bigger program. Maybe even two.
Please don't talk about what you don't know. Standard Chartered's Haskell compiler is written completely from scratch and is not based on any existing compiler.