Mark Seemann • 2/9/2026

Simplifying assertions with lenses

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This technical article discusses a common problem in software testing: writing weak or awkward assertions for nested record types. Using Haskell as an example, it demonstrates how the lens library, specifically the 'both' function, can be used to create more precise and readable test comparisons, moving beyond simple equality checks to target specific parts of complex data.

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#testing #functional programming #assertions
Simplifying assertions with lenses

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