  Modern software engineering often involves using many existing APIs, both
open source and, in industrial coding environments, proprietary. Programmers
reference documentation and code search tools to remind themselves of proper
common usage patterns of APIs. However, high-quality API usage examples are
computationally expensive to curate and maintain, and API usage examples
retrieved from company-wide code search can be tedious to review. We present a
tool, EG, that mines codebases and shows the common, idiomatic usage examples
for API methods. EG was integrated into Facebook's internal code search tool
for the Hack language and evaluated on open-source GitHub projects written in
Python. EG was also compared against code search results and hand-written
examples from a popular programming website called ProgramCreek. Compared with
these two baselines, examples generated by EG are more succinct and
representative with less extraneous statements. In addition, a survey with
Facebook developers shows that EG examples are preferred in 97 percent of
cases.
