Fill-in-the-Middle: The Magic Behind Smart Code Completion

How your favorite code editor suggests exactly what you were thinking of

Fill-in-the-Middle (FIM) is a technique in code completion that allows language models to generate code based on context from both before and after the cursor. Unlike traditional left-to-right autocompletion, which only sees past code, FIM provides a "peek into the future," enabling significantly more accurate and contextually aware suggestions. The technique was popularized by OpenAI's 2022 paper, "Efficient Training of Language Models to Fill in the Middle", which detailed an effective method for training models on this task. This approach has since become a cornerstone for many…

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• Varun Goyal

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