E022: An exported constant needs a value Turf can know right away

export immut shares a constant with every file that imports it, but it does that by baking the literal value directly into each importing file at compile time – there’s no shared storage behind the scenes. That means the value has to be something Turf can figure out immediately, like a plain number, string, or true/false, not something computed from another variable or a function call.

immut base: int = 10;export immut total: int = base * 2;

Even though base * 2 is obviously 20 to a person reading this, Turf’s exported constants can only hold a literal value written directly, not an expression – even a simple one like this. The fix is just to write out the actual value:

export immut total: int = 20;

If the real value genuinely needs to be computed (not just a simple literal you can write by hand), it can’t be an exported constant. Instead, keep it as a normal (non-exported) variable and compute it wherever it’s actually used:

immut base: int = 10;immut total: int = base * 2;   // fine -- not exported, so any expression works

This is a small tradeoff for how export immut works, but it’s a fair one: it means every file that imports a constant gets a value with zero runtime cost, right there at compile time.

The same rule explains the other way to trip this error: leaving the value out altogether.

export immut MAX_RETRIES: int;      // nothing to export

An exported constant is its value, so it has to be given one on the spot:

export immut MAX_RETRIES: int = 3;

Run turf --explain E022 in a terminal to read this again.