Swipe Type

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Swipe typing lets you draw a path across the keyboard instead of tapping individual keys. This predictor matches your input pattern against a word list.

Each word is converted to a path on a QWERTY keyboard layout. The algorithm uses Dynamic Time Warping (DTW) to measure how similar your swipe path is to each word's path. Words with similar paths get low scores.

Word frequency from a corpus is used as a tiebreaker—common words rank higher when paths are equally close.

Try these swipe patterns:

• asdfghjkl;poiuygfdsascsa → alpaca
• poiuytrernmngyuijnb → penguin

Optimizations

To run DTW (an O(n×m) algorithm) against 333k words in milliseconds entirely client-side, we needed some optimizations. The engine is written in Rust and compiled to WebAssembly:

• Sakoe-Chiba band — constrain DTW to a diagonal band, reducing complexity to O(n×w)
• Early termination — prune candidates mid-computation if partial score exceeds current best
• O(n) space — keep only two rows of the DTW matrix in memory
• First/last character filtering — only consider words matching the first character; penalize last character mismatches

Source