literalif

Literalif is a proposed conditional construct in programming language design that returns one of two literal values based on a condition, with an emphasis on preserving literal values and enabling compile-time evaluation.

Syntax and semantics: literalif (condition, trueValue, falseValue). Both trueValue and falseValue are intended to be literals or expressions that can be reduced to literals without runtime computation. If the condition is known at compile time, many implementations can fold the result to a single literal, potentially improving constant folding and code generation.

Examples: literalif (flag, 1, 0) yields 1 when flag is true, otherwise 0. literalif (env == "prod", "minified", "debug") yields a string literal depending on the environment.

Typing and rules: the resulting type of literalif is typically the common literal type of trueValue and falseValue. If the two branches produce incompatible types, a language may report a type error or promote to a compatible supertype. Side effects in the branches are generally discouraged or disallowed to preserve purely literal semantics.

Implications and limitations: literalif aims to improve compile-time evaluation and observability of literal values, but it is not part of major language standards. Adoption discussions address how it interacts with existing conditionals, type systems, and macro facilities, as well as potential readability concerns and limitations when branches cannot be expressed as literals.

History and related concepts: The idea appears in language-design discussions and experimental features focused on literal-oriented evaluation and macro systems. Related concepts include the standard if-else construct, the ternary operator, and compile-time evaluation mechanisms.