Traps and runtime failures

Static checking prevents many invalid operations, but some facts are known only while a program runs. Pop uses traps for violated runtime checks.

The native runtime distinguishes these core trap reasons:

• integer overflow;
• division by zero;
• bounds violation;
• an impossible internal state.

For example, this passes type checking because both values are UInt8, but it traps when the addition exceeds the type’s maximum:

local value: UInt8 = 255
local next = value + 1

Likewise, Array.get(values, index) and indexed assignment trap when index is outside the one-based array bounds.

Ordinary array indexing is the non-trapping alternative for reads: values[index] returns nil when no element exists. Choosing between the two forms communicates whether absence is an expected outcome or an invariant violation.

Traps are not recoverable results

Pop 0.1.0-rc.2 does not expose a source-level exception mechanism for catching these traps. A trap stops normal program execution. Validate user input and array positions before using operations whose preconditions may not hold.

Runtime invariants and out-of-memory conditions are separate fatal failures rather than ordinary Pop values. Although names such as Result<T, E> exist in the compiler’s bootstrap type universe, a general Pop-facing result library and exception-handling framework are not implemented in this release.