[lmm]

> 1) Pretty easy to guarantee if main looks like stage1(); stage2(); stage3(); etc.

You can only use the global program order once, I'd rather save it to spend on something more important. val result1 = stage1(); val result2 = stage2(result1); ... means my code dependencies reflect my data dependencies and I'll never get confused about what needs what or comes before or after what (or the compiler will catch me if I do), so I can refactor fearlessly.

> 2) Change a plus for a minus and it is still an int.

True. If you get your core business logic wrong then types won't help you with that (though FWIW I'd argue that it's worth having a distinct type for natural numbers, in which case - and + return different types). But I found that at least 80% of production bugs weren't errors in core business logic but rather "silly little things": nulls, uncaught exceptions, transposed fields... and types catch those more cheaply cheaper than any alternative I've seen.