Re: [RFC] [Discussion] Literal Scalar Types

On Mon, 15 Jun 2026 at 19:43, Tim Düsterhus <tim@bastelstu.be> wrote: > > Hi > > On 6/15/26 03:22, Seifeddine Gmati wrote: > > I'd like to start the discussion on a new RFC adding literal scalar > > types to PHP. > > > > - RFC: https://wiki.php.net/rfc/literal_scalar_types > > - Implementation: > > https://github.com/php/php-src/pull/22314 > > I have given the RFC a quick first review pass and would suggest to > leave out support for float literals. From a conceptual perspective > floats are much closer to being continuous values than they are to > discrete values and picking individual values from a continuous range is > typically not all that useful. > > Support for floats is also going to invite the usual confusion about > implicit rounding: > > function tenths( > 0.0|0.1|0.2|0.3|0.4|0.5|0.6|0.7|0.8|0.9 $tenth > ): void { var_dump($tenth); } > > where tenths(0.1 + 0.2) will result in a TypeError. The RFC is > also > unclear what values are valid floating point literals. As an example, is > 4e3 a valid float literal? Is NAN a valid float literal? > > Best regards > Tim Düsterhus Hi Tim, I think I might agree here, and others have raised the same concern on Discord. Dropping float literals for now simplifies the RFC, so I am inclined to do that, though I would like to hear what others think before removing them. For what it is worth, I am personally fine with tenths(0.1 + 0.2) failing to match 0.3. This is not new behaviour: 0.1 + 0.2 == 0.3 is already false, and a match (0.1 + 0.2) already skips a 0.3 arm for exactly the same reason. So a literal float type behaves consistently with comparison and match, rather than introducing a new surprise. On your concrete questions: 4e3 is a valid float literal and works today; it normalizes to 4000.0 (the type also stringifies as 4000.0). NAN and INF, on the other hand, are not literals but constant identifiers that go through constant resolution. They are out of scope for the same reason FOO is above: NAN $foo could just as well mean a class named NAN.