Dev Tools · 1h ago
Why Your Calculator App Is Probably Wrong About Units
A developer's deep dive into a civil-engineering calculator reveals that most calculator apps fail not due to math errors but unit mismatches. Weakly typed numbers allow bugs like confusing millimetres with metres or mixing material densities, leading to five-figure errors on large jobs. The fix involves encoding units and domain distinctions into code, turning silent mistakes into explicit crashes.
Meridian48 take
The article's lesson—that unit errors are more dangerous than logic errors—is a crucial reminder for any developer building domain-specific tools, but the proposed solutions (tagged objects or branded types) are well-known patterns, not novel insights.
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