pattern-wishcast 0.0.1-pre.7

Pattern types emulation for conditional variants using conditional never types
Documentation 
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// SPDX-FileCopyrightText: 2025 LunNova
//
// SPDX-License-Identifier: MIT

use pattern_wishcast::pattern_wishcast;

pattern_wishcast! {
	/// Stuck evaluation states
	#[derive(Debug, Clone, PartialEq)]
	enum StuckValue = {
		/// Unresolved variable
		Free { index: usize },
	};

	/// Main value type with strum discriminants
	#[derive(Debug, Clone, PartialEq, strum::EnumDiscriminants)]
	#[strum_discriminants(derive(strum::IntoStaticStr))]
	enum Value is <P: PatternFields> = StuckValue | {
		/// Fully evaluated number
		Number { value: i32 },
	};

	type StrictValue = Value is Number { .. };
	type FlexValue = Value is _;

	#[derive(SubtypingRelation(upcast=to_flex, downcast=try_to_strict))]
	impl StrictValue : FlexValue;
}

impl FlexValue {
	pub fn kind_name(&self) -> &'static str {
		ValueDiscriminants::from(self).into()
	}
}

#[test]
fn test_strum_discriminants() {
	let v = FlexValue::Number { value: 42 };
	assert_eq!(v.kind_name(), "Number");

	let stuck = FlexValue::StuckValue(StuckValue::Free { index: 0 }, ());
	assert_eq!(stuck.kind_name(), "StuckValue");
}