Generalize do-expressions to statements in general?

Herby Vojčík herby at
Thu Jul 16 20:36:22 UTC 2015

Herby Vojčík wrote:
> Mark S. Miller wrote:
>> I echo this. E is a dynamic language with many similarities with JS,
>> including a similarly C-like syntax. In E I use
>> everything-is-a-pattern-or-expression all the time. When I first moved
>> to JS I missed it. Now that I am used to the JS
>> statements-are-not-expressions restrictions, I no longer do, with one
>> exception:
>> When simply generating simple JS code from something else, this
>> restriction is a perpetual but minor annoyance. By itself, I would agree
>> that this annoyance is not important enough to add a new feature.
>> However, if rather than "adding a feature", we can explain the change as
>> "removing a restriction", then JS would get both simpler and more
>> powerful at the same time. Ideally, the test would be whether, when
>> explaining the less restrictive JS to a new programmer not familiar with
>> statement languages, this change results in one less thing to explain
>> rather than one more.
> I like the idea those it seems a bit dense and strange on the first
> look. One breaking change is, though, that before the change, semicolon
> inside parentheses is an error, which often catches the missing
> parenthesis; after the change it is not (and manifests itself only at
> the end of the file; or even two errors can cancel each other and make
> conforming JS but with different semantics).
>> On Thu, Jul 16, 2015 at 6:38 AM, Andreas Rossberg <rossberg at
>> <mailto:rossberg at>> wrote:
>> On 16 July 2015 at 15:21, Bob Myers <rtm at
>> <mailto:rtm at>> wrote:
>> With all "do" respect, none of this syntax tinkering makes any
>> sense to me.
>> I've been programming JS for 15 years and never noticed I needed
>> a try block that returns a value.
>> Long ago I programmed in a language called AED that had valued
>> blockl, which I was quite fond of, but never felt the need for
>> that in JS for whatever reason.
>> I've been programming in C++ for 25 years, and didn't have much need
>> for a try expression or nested binding either.
>> I've also been programming in functional languages for 20 years, and
>> need them on a regular basis.
>> It all depends on how high-level your programming style is. Also,
>> Sapir Whorf applies as usual.
>> /Andreas
>> --
>> Cheers,
>> --MarkM
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