Destructuring let with failure #80
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janmasrovira
approved these changes
Aug 25, 2025
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The
let! pat := v; bsyntax desugars tomatch v with | pat => b | _ => default. The value returned on failure (instead ofdefault, whenvdoes not matchpat) can be specified with thefailwithclause:let! pat := v failwith failure; b. The monadic versionlet! x ← mv; bcan be used whenmv : m Vfor some monadm. The type ofpatcan be specified.