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Having semicolons introduces simple redundancy to the language. If you leave off semicolons you introduce more ambiguity, which can make error messages less cle

Having semicolons introduces simple redundancy to the language. If you leave off semicolons you introduce more ambiguity, which can make error messages less clear since it's less obvious to the compiler exactly what was the mistake the programmer made. Think of it like a sliding scale: on the far extreme of no redundancy, a typo could be a runtime error instead of a compile error. On the far extreme of redundancy, you have to express your code twice in different ways. Having semicolons is a reasonable balance between the extremes.

roryokane 11y ago
I think I understand why semicolons make good error messages easier to implement. However, I don't see anything that makes that same quality of error messages impossible in a language without semicolons. It's just a matter of how much time the language writer is willing to spend on slightly improving the user experience. Semicolons help get a better error message for the following typo, if `foo` can take either 0 or 1 arguments: if (true) { foo(; bar *= 2; baz( "first", "second", ); } The compiler can easily tell you that you forgot a ) on line 2. If semicolons were optional, the program would be this: if (true) { foo( bar *= 2 baz( "first", "second", ) } The simplest error message to implement would complain that you forgot a ) somewhere within lines 2 to 7, and also that the argument to `foo` contains two statements instead of one expression. This error message would be less helpful. However, with the semicolonless language, you could still write the compiler to give the better error message. You could have a heuristic that that this combination of errors suggests a different error, or you could parse indentation for error-checking purposes. It would just require more work on the part of the compiler writer.

roryokane 11y ago

I think I understand why semicolons make good error messages easier to implement. However, I don't see anything that makes that same quality of error messages impossible in a language without semicolons. It's just a matter of how much time the language writer is willing to spend on slightly improving the user experience. Semicolons help get a better error message for the following typo, if `foo` can take either 0 or 1 arguments: if (true) { foo(; bar *= 2; baz( "first", "second", ); } The compiler can easily tell you that you forgot a ) on line 2. If semicolons were optional, the program would be this: if (true) { foo( bar *= 2 baz( "first", "second", ) } The simplest error message to implement would complain that you forgot a ) somewhere within lines 2 to 7, and also that the argument to `foo` contains two statements instead of one expression. This error message would be less helpful. However, with the semicolonless language, you could still write the compiler to give the better error message. You could have a heuristic that that this combination of errors suggests a different error, or you could parse indentation for error-checking purposes. It would just require more work on the part of the compiler writer.