Deferred execution

Keep code for later

Prerequisites: Blocks and Scope and imports. A deferred value keeps code as a value until something asks to evaluate it. Use an ordinary function when the only goal is to reuse a calculation; deferral is for code that must be inspected or evaluated at a chosen time.

@{; ... } holds a block; .Eval() runs it. The output is 5.

Runnable RiXRun cell

later := @{; 2 + 3 }; later.Eval();

Change the addition to multiplication and predict the result. The block is not evaluated merely by binding later.

Choose the evaluation boundary

.Eval can also evaluate a source string. @@later evaluates a deferred value directly in the caller's scope, so caller-visible names and updates require care. Keep ordinary functions and blocks for everyday calculations; use dynamic evaluation only when the scope is intentional.

Runnable RiXRun cell

later := @{; 2 + 3 }; @@later;

Continue with RiX scripts for reusable programs with explicit capability boundaries.