Steve McCanne

This commit removes double slash comments to align with SQL as we already support SQL style comments (--).

This commit enables multi-line comments in the PEG grammar. We had a past issue with making this work but it just works now in the current grammar.

We should decide whether the distinct pipe operator stays in the language or is hidden for use only by sql distinct. If we include it, we need to document it.

csv reader should have a strings only option

1

From zio/csvio/reader.go: ``` // XXX This is a placeholder for an option that will allow one to convert // all csv fields to strings and defer any type coercion presumably...

join-key expressions are too fussy

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The join-key expressions currently work on each side's respective table. You should be able to refer to either side on either side of the join expression. The cut-expressions will continue...

anti join assignments

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The semantic analyzer should check that an anti join does not specify join assignments as the right-hand side is undefined in anti matches. An error should be reported if such...