--- title: [RFC] [Discussion] Literal Scalar Types | daily.dev description: A PHP internals mailing list thread discussing a proposed RFC to add literal scalar types to PHP, allowing function signatures to express exact accepted values... canonical: https://daily.dev/posts/rfc-discussion-literal-scalar-types-9lcrg8ptz twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: [RFC] [Discussion] Literal Scalar Types | daily.dev og:description: A PHP internals mailing list thread discussing a proposed RFC to add literal scalar types to PHP, allowing function signatures to express exact accepted values... og:url: https://daily.dev/posts/rfc-discussion-literal-scalar-types-9lcrg8ptz og:image: https://api.daily.dev/og/posts/9lcrG8PTZ.png og:image:alt: [RFC] [Discussion] Literal Scalar Types og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # [RFC] [Discussion] Literal Scalar Types **[externals.io](https://daily.dev/sources/externals)** · 10 min read · 0 upvotes · 0 comments ## Summary A PHP internals mailing list thread discussing a proposed RFC to add literal scalar types to PHP, allowing function signatures to express exact accepted values like `0|1|2` or `"ascii"|"utf-8"`. The RFC author argues these complement enums by covering three gaps: describing existing scalar APIs without breaking callers, supporting open/extensible value sets without the overhead of a named enum, and enabling direct scalar interop (array keys, JSON, strict equality). Skeptics note backed enums already handle much of this. A community member also suggests extending the idea to numeric ranges like `-1..1` or `1..PHP_INT_MAX`, which the author acknowledges as a logical follow-up but proposes keeping as a separate RFC due to added design complexity around bounds, coercion, and open-ended ranges. ## Full article daily.dev links to this article rather than hosting it. 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