What does the presence of the double comma, (,,) before the where phrase part of a parsed select statement.
I know a single comma means it is enlisted
What are the implications in terms of converting to a functional statement
The list of constraints (index 2) is itself a parse tree which means value cannot be applied to the output of parse. For a simple example like this, it's just a matter of removing a level of nesting but just to illustrate....
(btw, your example has a bug: size should not be a symbol in your q-sql statement as it's a column name)
q)show t:(a:1 2;b:10 20); a b ---- 1 10 2 20 q)show pt:parse"select from t where a>1"; // parse tree at index 2 ? `t ,,(>;`a;1) 0b () q)value pt // value cannot be applied 'type  value pt // value cannot be applied ^ q)@[pt;2;eval] // evalute the parse tree at index 2 which removes a level of nesting ? `t ,(>;`a;1) 0b () q) q)value @[pt;2;eval] // value can be applied to output a b ---- 2 20 q) q)?[t;enlist(>;`a;1);0b;()] ~ value @[pt;2;eval] // matches manually typed functional form 1b
Some further reading which includes more complex examples https://code.kx.com/q/wp/parse-trees/
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