Adding some macro features refs #2514

doc/Language/experimental.pod6

@@ -33,8 +33,41 @@ on via the pragma
 
     use experimental :macros;
 
-Macro processing happens during parsing time.
-
+Macro processing happens during parsing time. A macro generates an abstract
+syntax tree, which is grafted into the program syntax tree. C<quasi> is the
+routine that performs this task.
+
+=begin code :skip-test<need use experimental>
+macro does-nothing() {
+    quasi {}
+};
+does-nothing; # OUTPUT: «»
+=end code
+
+X<|quasi (macros)>
+Macros are a kind of routine, so they can take arguments in exactly the same
+way, and act also in almost the same way.
+
+=begin code :skip-test<need use experimental>
+macro is-mighty( $who ) {
+    quasi { "$who is mighty!"}
+};
+say is-mighty "Freija"; # OUTPUT: « "Freija" is mighty!␤»
+=end code
+
+X<|unquoting (macros)>
+X<|{{{}}} (macros)>
+"Almost" accounts for the fact that the argument is inserted as a literal,
+including the quotes. Please note that we can also eliminate the parentheses for
+a macro call, following the same rules as a routine. You can use the unquoting
+construct C<{{{}}}> to get rid of this kind of thing:
+
+=begin code :skip-test<need use experimental>
+macro is-mighty( $who ) {
+    quasi { {{{$who}}} ~ " is mighty!"}
+};
+say is-mighty "Freija";# OUTPUT: «Freija is mighty!␤»
+=end code
 
 
 =end pod