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Update varargs syntax in quote pattern examples #2980

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Mar 1, 2024
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Update varargs syntax in quote pattern examples #2980

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10 changes: 5 additions & 5 deletions _overviews/scala3-macros/tutorial/quotes.md
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Original file line number Diff line number Diff line change
Expand Up @@ -156,11 +156,11 @@ given ToExpr[Boolean] with {
given ToExpr[StringContext] with {
def apply(stringContext: StringContext)(using Quotes) =
val parts = Varargs(stringContext.parts.map(Expr(_)))
'{ StringContext($parts: _*) }
'{ StringContext($parts*) }
}
```
The `Varargs` constructor just creates an `Expr[Seq[T]]` which we can efficiently splice as a varargs.
In general, any sequence can be spliced with `$mySeq: _*` to splice it as a varargs.
In general, any sequence can be spliced with `$mySeq*` to splice it as a varargs.

## Quoted patterns
Quotes can also be used to check if an expression is equivalent to another or to deconstruct an expression into its parts.
Expand Down Expand Up @@ -352,7 +352,7 @@ Types represented with `Type[T]` can be matched on using the patten `case '[...]
inline def mirrorFields[T]: List[String] = ${mirrorFieldsImpl[T]}

def mirrorFieldsImpl[T: Type](using Quotes): Expr[List[String]] =

def rec[A : Type]: List[String] = Type.of[A] match
case '[field *: fields] =>
Type.show[field] :: rec[fields]
Expand Down Expand Up @@ -408,8 +408,8 @@ given FromExpr[Boolean] with {

given FromExpr[StringContext] with {
def unapply(x: Expr[StringContext])(using Quotes): Option[StringContext] = x match {
case '{ new StringContext(${Varargs(Exprs(args))}: _*) } => Some(StringContext(args: _*))
case '{ StringContext(${Varargs(Exprs(args))}: _*) } => Some(StringContext(args: _*))
case '{ new StringContext(${Varargs(Exprs(args))}*) } => Some(StringContext(args*))
case '{ StringContext(${Varargs(Exprs(args))}*) } => Some(StringContext(args*))
case _ => None
}
}
Expand Down
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