For me, && is more natural than "when" because i've written more
switch that uses && than "when".
And don't forget that unlike most of the code, with pattern matching
the number of characters does matter, this is more similar to
lambdas, if what you write is too verbose, you will not write it.
At the risk of premature bikeshedding, have we already discussed and
discarded the idea of spelling “when” as “if”? It’s been a long time,
and I forget.
There was not extensive discussion on this, and its all very
subjective/handwavy/"what we think people would think", but I remember a
few comments on this:
- The generality of "if" reminded people of the Perl-style "statement
unless condition" postfix convention, and that people might see it as an
"inconsistency" that they could not then say
x = 3 if (condition);
which is definitely somewhere we don't want to go.
- We're use to seeing "if" with a consequence, and a "naked" if might
have the effect of "lookahead pollution" in our mental parsers.
- Keeping `if` for statements allows us to keep the "body" of case
clauses visually distinct from the "envelope":
case Foo(var x)
if (x > 3) : if (x > 10) { ... }
would make people's eyes go buggy. One could argue that "when" is not
fantastically better:
case Foo(var x)
when (x > 3) : if (x > 10) { ... }
but it doesn't take quite as long to de-bug oneself in that case.
On 2/15/2022 9:55 PM, Guy Steele wrote:
