BlinkFill: Semi-supervised Programming By Example for Syntactic String Transformations

The recent Programming By Example (PBE) techniques such as FlashFill have shown great promise for enabling end-users to perform data transformation tasks using inputoutput examples. Since examples are inherently an underspecification, there are typically a large number of hypotheses conforming to the examples, and the PBE techniques suffer from scalability issues for finding the intended program amongst the large space. We present a semi-supervised learning technique to significantly reduce this ambiguity by using the logical information present in the input data to guide the synthesis algorithm. We develop a data structure InputDataGraph to succinctly represent a large set of logical patterns that are shared across the input data, and use this graph to efficiently learn substring expressions in a new PBE system BlinkFill. We evaluate BlinkFill on 207 real-world benchmarks and show that BlinkFill is significantly faster (on average 41x) and requires fewer input-output examples (1.27 vs 1.53) to learn the desired transformations in comparison to FlashFill.