问题
I struggled with this for hours before finding out that you have to use from_ instead of from when using gremlin javascript.
After digging through the source code I finally found out that the code is using from_ instead of from (see code). Since I'm a newbie this comes off as strange because its counterpart to is still to (and not to_, see code here)
I googled everywhere but couldn't find the reason why this works this way, and feel uneasy about using the underscore version since most of the times underscores denote private methods that users should not really trust.
Also, is there an official documentation page for gremlin javascript somewhere I'm missing? I'm concerned I may run into these problems in the future and there's not really an official documentation for the JavaScript version and I may need to go through the same struggle. I like gremlin, but if the JavaScript version is not stable and should not be used, I might as well look into other alternatives than Tinkerpop suites.
回答1:
Gremlin Language Variants (GLVs) are given some latitude in terms of how they implement the Gremlin language so that it feels as close to the syntax and programming idioms of the native language and thus avoid too much pollution from Java. In other words, if you're using gremlin-javascript it should feel like your coding in JS and not Java. So, you will see slight differences among GLVs from time to time.
So, with respect to from_ specifically, we typically use an underscore when we have a conflict in a native language with a reserved keyword. In Java from is fully acceptable, but in other languages it is not. For Javascript, from is currently not a reserved word, but we are preparing for the eventual form of import ... from which is coming in the future.
As for documentation, I'm not aware of too much more than what you have already found on the TinkerPop web site. We hope to have more examples and information available in our next release.
来源：https://stackoverflow.com/questions/51374763/why-does-gremlin-javascript-use-from-mapping-instead-of-from