James, are you commenting on felix's idea of strict expressions (in which case, I suggest the other thread: https://esdiscuss.org/topic/strict-non-coercing-expressions), or strict relational operators?
Other than felix's strict expressions, I don't think anyone was suggesting that strict relational operators should throw. It would be important that they behave consistently with `===` and `!==`: Just result in `false` when the types don't match. -- T.J. Crowder On Thu, Apr 13, 2017 at 12:29 PM, James Treworgy <[email protected]> wrote: > I am of the opinion that this isn't really a worthwhile effort in the > context of a non-typed language. There are several issues. > > First, it doesn't actually create any parity with ===. Triple equals never > throws an error, it just returns false if the types are unequal. These > constructs would change the way the language works fundamentally in that an > expression can cause an error which it currently cannot. > > Second, it really just provides a kind of "too late" poor man's type > checking. What you really wanted was a guard when the variable was created > or the argument passed. It may provide little help about the actual source > of the bug. > > New syntax and the complexity it creates seems a high price to pay for a > little band aid. > > If we were going to add some simple syntax to try to help this problem > without going full typescript/flow then I'd be much more in favor of simply > adding type guard clauses to function arguments that are evaluated at > runtime. > > > On Apr 13, 2017 2:44 AM, "T.J. Crowder" <[email protected]> > wrote: > >> I've started a separate thread to discuss felix's idea of an expression >> mode making all operators within it non-coercing (as it's rather more broad >> than this topic): https://esdiscuss.org/topic/st >> rict-non-coercing-expressions >> >> -- T.J. Crowder >> >> >> On Thu, Apr 13, 2017 at 6:58 AM, Darien Valentine <[email protected]> >> wrote: >> >>> > It's reasonable for non-coercing === to work on different types, but what >>> would a non-coercing + do with different types? It has to throw an >>> error. >>> >>> Ah, didn’t catch that you were talking about non-relational operators as >>> well. Assuming a strict `+` was still overloaded for string concatenation, >>> yeah, an error makes sense (whereas if numeric only, NaN might also be >>> considered a reasonable answer). >>> >>> For strict `<`, etc, I think it would be unintuitive to get an error or >>> to have arbitrary type order. Rather I’d expect it to be false when the >>> types didn’t match, since, for example, the correct answer to both the >>> questions "is seven greater than an object?" and "is an object greater than >>> 7?" is "no". This would be consistent with the behavior of the existing >>> always-incomparable value, NaN, as well. That said, I think an error would >>> be better than having an arbitrary type order if those were the two choices. >>> >>> On Thu, Apr 13, 2017 at 12:56 AM, felix <[email protected]> wrote: >>> >>>> On Wed, Apr 12, 2017 at 7:23 PM, Darien Valentine < >>>> [email protected]> wrote: >>>> >> One common JS problem is NaNs ending up in unexpected places, and >>>> it's >>>> >> often difficult to trace back where they came from. Getting a type >>>> error >>>> >> instead of a NaN would be nice. >>>> > >>>> > I’m not sure this would help with that. NaN may be the product of >>>> coercion, >>>> > but NaN itself is a numeric value, and it can be produced without any >>>> type >>>> > coercion, e.g. `Infinity/Infinity`, `(-1) ** 0.5`, etc. And the `===` >>>> > operator is a strict, non-coercive comparison, but that doesn’t mean >>>> it >>>> > throws type errors. >>>> >>>> Mysterious NaNs in js are usually due to implicit conversion of random >>>> objects to numbers, not normal numeric computation. >>>> >>>> It's reasonable for non-coercing === to work on different types, but >>>> what would a non-coercing + do with different types? It has to throw >>>> an error. >>>> >>>> Non-coercing < might throw an error or use some arbitrary ordering of >>>> types. I don't have strong feelings about that. >>>> >>> >>> >>> _______________________________________________ >>> es-discuss mailing list >>> [email protected] >>> https://mail.mozilla.org/listinfo/es-discuss >>> >>> >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >>
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