Skip to content
FScript

Runtime Overview

Runtime Overview

The runtime exists to execute well-typed FScript programs efficiently and predictably without depending on a JavaScript engine.

Core responsibilities

  • program startup
  • module initialization
  • execution of effectful tasks
  • implicit suspension and resumption
  • generator state management
  • native implementations of std: modules
  • error propagation across host boundaries

Core principles

  • pure code should not pay async scheduler overhead
  • effectful work may suspend implicitly
  • effectful calls start eagerly by default
  • defer is the explicit tool for laziness

What this means in practice

FScript source often looks sequential even when effectful work is involved. The runtime, not Promise syntax in user code, coordinates when work starts and when execution needs to wait for results.