#s_exp `s_exp @s_exp
Normally Gamma evaluates every expression as it parses through the code. The # operator protects the contents of an expression from the evaluator. The ` operator does the same thing, but allows for evaluation of sub-expressions. Any sub-expression tagged with @ operator that occurs within a back-ticked (`) expression will be evaluated.
Any error messages involving the @ operator will use the expression _comma_. This is because the @ operator in Gamma corresponds to a comma operator (,) in Lisp syntax. When a Gamma expression is passed to Lisp, the @ operator is converted to a comma. But if the Lisp comma operator is ever read back into Gamma, it is represented by the symbol _comma_ to avoid confusion with the (,) operator used in Gamma function calls.
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