Mercurial Hosting > luan
changeset 389:497d4ef0a89f
documentation work
| author | Franklin Schmidt <fschmidt@gmail.com> |
|---|---|
| date | Fri, 24 Apr 2015 12:25:50 -0600 |
| parents | 12ee9a336b95 |
| children | bfbbce690bba |
| files | website/src/diff.html.luan website/src/manual.html.luan |
| diffstat | 2 files changed, 56 insertions(+), 75 deletions(-) [+] |
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--- a/website/src/diff.html.luan Thu Apr 23 18:54:35 2015 -0600 +++ b/website/src/diff.html.luan Fri Apr 24 12:25:50 2015 -0600 @@ -131,19 +131,19 @@ <p>Luan has no numeric <b>for</b> statement. Luan only has generic <b>for</b> statement. Instead of the numeric <b>for</b> statement, Luan uses the <tt>range</tt> function in a generic <b>for</b> statement like this:</p> -<tt><pre> +<p><tt><pre> for i in range(from,to,step) do <i>block</i> end - </pre></tt> +</pre></tt></p> - <p>The Luan generic <b>for</b> statement is simpler than the Lua version because Luan only uses and expression, not an explist. So a <b>for</b> statement like:</p> +<p>The Luan generic <b>for</b> statement is simpler than the Lua version because Luan only uses and expression, not an explist. So a <b>for</b> statement like:</p> - <tt><pre> +<p><tt><pre> for var_1, ยทยทยท, var_n in exp do block end - </pre></tt> +</pre></tt></p> - <p>is equivalent to the code:</p> +<p>is equivalent to the code:</p> - <tt><pre> +<p><tt><pre> do local f = exp while true do @@ -152,37 +152,37 @@ block end end -</pre></tt> +</pre></tt></p> <h4 margin-top="1em"><a name="logical">Logical Statements</a></h4> <p>Unlike Lua, Luan allows <b>or</b> and <b>and</b> expressions to be stand-alone statements. This is useful in cases like this:</p> -<tt><pre> +<p><tt><pre> x==5 or error "x should be 5" -</pre></tt> +</pre></tt></p> <h4 margin-top="1em"><a name="template-stmt">Template Statements</a></h4> <p>Template statements are based on <a href="#template-expr">template exressions</a> and provide the full equivalent of <a href="http://en.wikipedia.org/wiki/JavaServer_Pages">JSP</a> but in a general way. Template statements write the equivalent template exression to standard output. For example:</p> -<tt><pre><%=Html.encode[[ +<p><tt><pre><%=Html.encode[[ local name = "Bob" %> Hello <%=name%>! Bye <%=name%>. <% -]]%></pre></tt> +]]%></pre></tt></p> <p>is equivalent to the code:</p> -<tt><pre><%=Html.encode[[ +<p><tt><pre><%=Html.encode[[ local name = "Bob" require("luan:Io").stdout.write( %> Hello <%=name%>! Bye <%=name%>. <% ) -]]%></pre></tt> +]]%></pre></tt></p> <h3 margin-top="1em"><a name="expr">Expressions</a></h3> @@ -202,17 +202,17 @@ <p>Luan adds a new type of expression based on <a href="http://en.wikipedia.org/wiki/JavaServer_Pages">JSP</a> called template expressions. Template expressions return multiple values. Here is an example:</p> -<tt><pre><%=Html.encode[[ +<p><tt><pre><%=Html.encode[[ local name = "Bob" write( %>Hello <%=name%>!<% ) -]]%></pre></tt> +]]%></pre></tt></p> <p>This is equivalent to the code:</p> -<tt><pre> +<p><tt><pre> local name = "Bob" write( "Hello ", name, "!" ) -</pre></tt> +</pre></tt></p> <p>The strings in template expressions may be multiple lines.</p>
--- a/website/src/manual.html.luan Thu Apr 23 18:54:35 2015 -0600 +++ b/website/src/manual.html.luan Fri Apr 24 12:25:50 2015 -0600 @@ -48,6 +48,12 @@ <ul> <li><a href="#lex">Lexical Conventions</a></li> <li><a href="#vars">Variables</a></li> + <li> + <a href="#stmts">Statements</a> + <ul> + <li><a href="#blocks">Blocks</a></li> + </ul> + </li> </ul> </div> @@ -525,12 +531,12 @@ and cannot be used as names: -<p><pre> +<p><tt><pre> and break do else elseif end false for function goto if in local nil not or repeat return then true until while -</pre></p> +</pre></tt></p> <p> Luan is a case-sensitive language: @@ -541,13 +547,13 @@ <p> The following strings denote other tokens: -<p><pre> +<p><tt><pre> + - * / % ^ # & ~ | << >> // == ~= <= >= < > = ( ) { } [ ] :: ; : , . .. ... -</pre></p> +</pre></tt></p> <p> <i>Literal strings</i> @@ -626,7 +632,7 @@ As an example the five literal strings below denote the same string: -<p><pre> +<p><tt><pre> a = 'alo\n123"' a = "alo\n123\"" a = '\97lo\10\04923"' @@ -635,7 +641,7 @@ a = [==[ alo 123"]==] -</pre></p> +</pre></tt></p> <p> A <i>numerical constant</i> (or <i>numeral</i>) @@ -652,17 +658,17 @@ otherwise it denotes an integer. Examples of valid integer constants are -<p><pre> +<p><tt><pre> 3 345 0xff 0xBEBADA -</pre></p> +</pre></tt></p> <p> Examples of valid float constants are -<p><pre> +<p><tt><pre> 3.0 3.1416 314.16e-2 0.31416E1 34e1 0x0.1E 0xA23p-4 0X1.921FB54442D18P+1 -</pre></p> +</pre></tt></p> <p> A <i>comment</i> starts with a double hyphen (<tt>--</tt>) @@ -691,9 +697,9 @@ (or a function's formal parameter, which is a particular kind of local variable): -<p><pre> +<p><tt><pre> var ::= Name -</pre></p> +</pre></tt></p> <p> Name denotes identifiers, as defined in <a href="#3.1">§3.1</a>. @@ -714,9 +720,9 @@ <p> Square brackets are used to index a table: -<p><pre> +<p><tt><pre> var ::= prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ -</pre></p> +</pre></tt></p> <p> The meaning of accesses to table fields can be changed via metatables. @@ -732,9 +738,9 @@ The syntax <tt>var.Name</tt> is just syntactic sugar for <tt>var["Name"]</tt>: -<p><pre> +<p><tt><pre> var ::= prefixexp ‘<b>.</b>’ Name -</pre></p> +</pre></tt></p> <p> An access to a global variable <tt>x</tt> @@ -746,10 +752,10 @@ -<h2>3.3 – <a name="3.3">Statements</a></h2> - -<p> -Lua supports an almost conventional set of statements, +<h3 margin-top="1em"><a name="stmts">Statements</a></h3> + +<p> +Luan supports an almost conventional set of statements, similar to those in Pascal or C. This set includes assignments, control structures, function calls, @@ -757,59 +763,34 @@ -<h3>3.3.1 – <a name="3.3.1">Blocks</a></h3> +<h3 margin-top="1em"><a name="blocks">Blocks</a></h3> <p> A block is a list of statements, which are executed sequentially: -<pre> +<p><tt><pre> block ::= {stat} -</pre><p> -Lua has <em>empty statements</em> +</pre></tt></p> + +<p> +Luan has <i>empty statements</i> that allow you to separate statements with semicolons, start a block with a semicolon or write two semicolons in sequence: -<pre> +<p><tt><pre> stat ::= ‘<b>;</b>’ -</pre> - -<p> -Function calls and assignments -can start with an open parenthesis. -This possibility leads to an ambiguity in Lua's grammar. -Consider the following fragment: - -<pre> - a = b + c - (print or io.write)('done') -</pre><p> -The grammar could see it in two ways: - -<pre> - a = b + c(print or io.write)('done') - - a = b + c; (print or io.write)('done') -</pre><p> -The current parser always sees such constructions -in the first way, -interpreting the open parenthesis -as the start of the arguments to a call. -To avoid this ambiguity, -it is a good practice to always precede with a semicolon -statements that start with a parenthesis: - -<pre> - ;(print or io.write)('done') -</pre> +</pre></tt></p> <p> A block can be explicitly delimited to produce a single statement: -<pre> +<p><tt><pre> stat ::= <b>do</b> block <b>end</b> -</pre><p> +</pre></tt></p> + +<p> Explicit blocks are useful to control the scope of variable declarations. Explicit blocks are also sometimes used to