# oops my scaler has a unit
x unit * x unit = x unit^2
The value isn’t catching this line of code since it’s potentially valid. It’s catching the line of code where you pass the result to a function that expects unit.
I agree, but the original article at dusted.codes hopes types will "prevent silly mistakes like multiplying $100 with £20".
I don't know what that author would think of multiplying $100 with $20, but my point is that this embrace of type systems is apparently not just about function interfaces; it also includes the operands of things like multiplication, and preventing that operation if the types are fishy.
For better or worse hopefully they think the two examples the same.
Using the example above, "multiplying $100 with £20" can be achieved just by making the better engineer a remote employee paid in pounds. It adds the exchange rate into the mix, so the math will change over time, but conceptually the math is the same as the "dollar * dollar" example.
