Add Product as upper type bound for asSchema

[manuzhang]

No description provided.

[MrPowers]

Related issue: #78

[MrPowers]

@manuzhang - this looks good. I don't really know too much about Product, but can infer what this is trying to do from your issue. Can you please write a test to demonstrate that this revised code is throwing a compile time error instead of a MatchError at runtime? Thanks!

[manuzhang]

@MrPowers Product is the superclass of both case class and Tuple. Not sure there is a way to expect a failure at compile time.

[MrPowers]

@manuzhang - thanks. If you and @snithish think this is good, then you're right that it should get merged. Adding it now.

Going to open an issue about potentially collaborating to open a Spark pull request for this function. This should probably be a core function offered by Spark.

[MrPowers]

@manuzhang - uTest has a compileError macro (https://github.com/lihaoyi/utest#compile-error) that "works similarly to intercept, except it does its checks (that a snippet of code fails) and errors (if it doesn't fail) at compile-time rather than run-time". Is it possible that we can use compileError to make sure the code you've added is working as expected in the test suite?

[manuzhang]

@MrPowers Interesting. Let me try

[manuzhang]

@MrPowers Please check out #91