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unreachable

Learn unreachable in WebAssembly through the exact construct, a dedicated example, a boundary case, and a mastery check.

10 min read • Intermediate

unreachable is an atomic WebAssembly lesson inside Control Flow. The example uses the specific syntax, command, API, instruction, or language rule named by this lesson.

Study the construct itself, then change one relevant input and predict the result before running it. That keeps this lesson focused on unreachable rather than on generic WebAssembly syntax.

Topic-specific example

webassembly-03-10.wat
wat Try It Live
(module (func (export "fail") unreachable))
Edge case / engineering note

For unreachable, check operand/result types and trap conditions. WebAssembly validation is strict even when the surrounding host code is permissive.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content