struct callerExpr
pub struct callerExpr :: [OnParameter]
Conforms to OnParameter.
Fills a string parameter with the source text the call wrote for parameter p.
@callerExpr(p) stands on a parameter with a default; where a call leaves that parameter
out, it gets the text written for p: assertEq(xs.length(), 3) hands std.test the words
xs.length(). Named like a compiler instruction, not like a type.