[zuzun]

> We have lost Mars climate orbiter due to not using type-safe language.

One company creates a closed-source component that produces a float, another company creates a closed-source component that receives a float. Units differ. Crash. No type-safe language will prevent that bug from happening. Let 100 programmers write these programs in your type-safe language of choice and all will be vulnerable to this.

"Oh no", I hear you say, "we'll give every unit its own type" and it still won't stop your programmers from deserializing a 4 byte value in English units into the metric value they think it is. "So we'll make all the IO typed as well!" You don't need a type safe language to do that. And why would you do it in the first place? If your API spec says you receive a float in metric units, you write your program accordingly. When you're writing mission critical software, would you really want to replace a

> read(sensor, &value, sizeof(float))

with 100k lines of even buggier code to prevent a bug from happening that shouldn't happen in the first place?

[fiedzia]

> Let 100 programmers write these programs in your type-safe language of choice and all will be vulnerable to this.

Some will be, some will define inteface as float_meters and define automatic conversion from yards, avoiding whole issue.

[lkitching]

All bugs "shouldn't happen in the first place", the use of types is to reduce the surface area for where errors can be introduced. If you read some value from an external source and subsequently use measure types then you've isolated the scope for the introduction of errors to the read function instead of every location in the program that uses the value.