Improve flow of documentation for non-standard strings (JuliaLang#40057)

Author: quildtide

doc/src/manual/metaprogramming.md

@@ -981,13 +981,13 @@ block:
 end
 ```
 
-## Non-Standard String Literals
+## [Non-Standard String Literals](@id meta-non-standard-string-literals)
 
 Recall from [Strings](@ref non-standard-string-literals) that string literals prefixed by an identifier are called non-standard
 string literals, and can have different semantics than un-prefixed string literals. For example:
 
-  * `r"^\s*(?:#|$)"` produces a regular expression object rather than a string
-  * `b"DATA\xff\u2200"` is a byte array literal for `[68,65,84,65,255,226,136,128]`.
+  * `r"^\s*(?:#|$)"` produces a [regular expression object](@ref man-regex-literals) rather than a string
+  * `b"DATA\xff\u2200"` is a [byte array literal](@ref man-byte-array-literals) for `[68,65,84,65,255,226,136,128]`.
 
 Perhaps surprisingly, these behaviors are not hard-coded into the Julia parser or compiler. Instead,
 they are custom behaviors provided by a general mechanism that anyone can use: prefixed string
@@ -1051,20 +1051,9 @@ constructed on each iteration. In the vast majority of use cases, however, regul
 are not constructed based on run-time data. In this majority of cases, the ability to write regular
 expressions as compile-time values is invaluable.
 
-Like non-standard string literals, non-standard command literals exist using a prefixed variant
-of the command literal syntax. The command literal ```custom`literal` ``` is parsed as `@custom_cmd "literal"`.
-Julia itself does not contain any non-standard command literals, but packages can make use of
-this syntax. Aside from the different syntax and the `_cmd` suffix instead of the `_str` suffix,
-non-standard command literals behave exactly like non-standard string literals.
-
-In the event that two modules provide non-standard string or command literals with the same name,
-it is possible to qualify the string or command literal with a module name. For instance, if both
-`Foo` and `Bar` provide non-standard string literal `@x_str`, then one can write `Foo.x"literal"`
-or `Bar.x"literal"` to disambiguate between the two.
-
 The mechanism for user-defined string literals is deeply, profoundly powerful. Not only are Julia's
-non-standard literals implemented using it, but also the command literal syntax (``` `echo "Hello, $person"` ```)
-is implemented with the following innocuous-looking macro:
+non-standard literals implemented using it, but the command literal syntax (``` `echo "Hello, $person"` ```)
+is also implemented using the following innocuous-looking macro:
 
 ```julia
 macro cmd(str)
@@ -1077,6 +1066,20 @@ but they are just functions, written entirely in Julia. You can read their sourc
 what they do -- and all they do is construct expression objects to be inserted into your program's
 syntax tree.
 
+Like string literals, command literals can also be prefixed by an identifier
+to form what are called non-standard command literals. These command literals are parsed
+as calls to specially-named macros. For example, the syntax ```custom`literal` ``` is parsed
+as `@custom_cmd "literal"`.
+Julia itself does not contain any non-standard command literals, but packages can make use of
+this syntax. Aside from the different syntax and the `_cmd` suffix instead of the `_str` suffix,
+non-standard command literals behave exactly like non-standard string literals.
+
+In the event that two modules provide non-standard string or command literals with the same name,
+it is possible to qualify the string or command literal with a module name. For instance, if both
+`Foo` and `Bar` provide non-standard string literal `@x_str`, then one can write `Foo.x"literal"`
+or `Bar.x"literal"` to disambiguate between the two.
+
+
 Another way to define a macro would be like this:
 
 ```julia

doc/src/manual/strings.md

@@ -739,13 +739,16 @@ Some other useful functions include:
 
 There are situations when you want to construct a string or use string semantics, but the behavior
 of the standard string construct is not quite what is needed. For these kinds of situations, Julia
-provides [non-standard string literals](@ref). A non-standard string literal looks like a regular
-double-quoted string literal, but is immediately prefixed by an identifier, and doesn't behave
-quite like a normal string literal.  Regular expressions, byte array literals and version number
-literals, as described below, are some examples of non-standard string literals. Other examples
-are given in the [Metaprogramming](@ref) section.
+provides non-standard string literals. A non-standard string literal looks like a regular
+double-quoted string literal,
+but is immediately prefixed by an identifier, and may behave differently from a normal string literal.
 
-## Regular Expressions
+[Regular expressions](@ref man-regex-literals), [byte array literals](@ref man-byte-array-literals),
+and [version number literals](@ref man-version-number-literals), as described below,
+are some examples of non-standard string literals. Users and packages may also define new non-standard string literals.
+Further documentation is given in the [Metaprogramming](@ref meta-non-standard-string-literals) section.
+
+## [Regular Expressions](@id man-regex-literals)
 
 Julia has Perl-compatible regular expressions (regexes), as provided by the [PCRE](http://www.pcre.org/)
 library (a description of the syntax can be found [here](http://www.pcre.org/current/doc/html/pcre2syntax.html)). Regular expressions are related to strings in two ways: the obvious connection is that