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edits for chapter 7

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@ -52,9 +52,9 @@ One of the great things about creating your own language is that you get to
decide what is good or bad. In this tutorial we'll assume that it is okay and decide what is good or bad. In this tutorial we'll assume that it is okay and
use this as a way to show some interesting parsing techniques.</p> use this as a way to show some interesting parsing techniques.</p>
<p>At the end of this tutorial, we'll <a href="#example">run through a nice <p>At the end of this tutorial, we'll run through an example Kaleidoscope
little example</a> that shows an example application that you can build with application that <a href="#example">renders the Mandelbrot set</a>. This gives
Kaleidoscope and the feature set it now has.</p> an example of what you can build with Kaleidoscope and its feature set.</p>
</div> </div>
@ -69,8 +69,8 @@ The "operator overloading" that we will add to Kaleidoscope is more general than
languages like C++. In C++, you are only allowed to redefine existing languages like C++. In C++, you are only allowed to redefine existing
operators: you can't programatically change the grammar, introduce new operators: you can't programatically change the grammar, introduce new
operators, change precedence levels, etc. In this chapter, we will add this operators, change precedence levels, etc. In this chapter, we will add this
capability to Kaleidoscope, which will allow us to round out the set of capability to Kaleidoscope, which will let the user round out the set of
operators that are supported, culminating in a more interesting example app.</p> operators that are supported.</p>
<p>The point of going into user-defined operators in a tutorial like this is to <p>The point of going into user-defined operators in a tutorial like this is to
show the power and flexibility of using a hand-written parser. The parser we show the power and flexibility of using a hand-written parser. The parser we
@ -262,7 +262,7 @@ a lot of similar code in the past. One interesting piece of this is the part
that sets up <tt>FnName</tt> for binary operators. This builds names like that sets up <tt>FnName</tt> for binary operators. This builds names like
"binary@" for a newly defined "@" operator. This takes advantage of the fact "binary@" for a newly defined "@" operator. This takes advantage of the fact
that symbol names in the LLVM symbol table are allowed to have any character in that symbol names in the LLVM symbol table are allowed to have any character in
them, inluding embedded nul characters.</p> them, even including embedded nul characters.</p>
<p>The next interesting piece is codegen support for these binary operators. <p>The next interesting piece is codegen support for these binary operators.
Given our current structure, this is a simple addition of a default case for our Given our current structure, this is a simple addition of a default case for our
@ -335,7 +335,7 @@ precedence parser, this is all we need to do to "extend the grammar".</p>
<p>With that, we have useful user-defined binary operators. This builds a lot <p>With that, we have useful user-defined binary operators. This builds a lot
on the previous framework we built for other operators. Adding unary operators on the previous framework we built for other operators. Adding unary operators
is a bit more challenging, because we don't have any framework for it yet, lets is a bit more challenging, because we don't have any framework for it yet - lets
see what it takes.</p> see what it takes.</p>
</div> </div>
@ -347,7 +347,7 @@ see what it takes.</p>
<div class="doc_text"> <div class="doc_text">
<p>Since we don't currently support unary operators in the Kaleidoscope <p>Since we don't currently support unary operators in the Kaleidoscope
langugage, we'll need to add everything for them. Above, we added simple language, we'll need to add everything for them. Above, we added simple
support for the 'unary' keyword to the lexer. In addition to that, we need an support for the 'unary' keyword to the lexer. In addition to that, we need an
AST node:</p> AST node:</p>
@ -530,8 +530,7 @@ def unary!(v)
def unary-(v) def unary-(v)
0-v; 0-v;
# Define &gt; with the same precedence as &gt;. We could also easily define # Define &gt; with the same precedence as &gt;.
# &lt;= etc.
def binary&gt; 10 (LHS RHS) def binary&gt; 10 (LHS RHS)
!(LHS &lt; RHS); !(LHS &lt; RHS);
@ -615,13 +614,13 @@ href="http://en.wikipedia.org/wiki/Mandelbrot_set">Mandelbrot Set</a>. Our
<tt>mandelconverge</tt> function returns the number of iterations that it takes <tt>mandelconverge</tt> function returns the number of iterations that it takes
for a complex orbit to escape, saturating to 255. This is not a very useful for a complex orbit to escape, saturating to 255. This is not a very useful
function by itself, but if you plot its value over a two-dimensional plane, function by itself, but if you plot its value over a two-dimensional plane,
you can see the mandelbrot set. Given that we are limited to using putchard you can see the Mandelbrot set. Given that we are limited to using putchard
here, our amazing graphical output is limited, but we can whip together here, our amazing graphical output is limited, but we can whip together
something using the density plotter above:</p> something using the density plotter above:</p>
<div class="doc_code"> <div class="doc_code">
<pre> <pre>
# compute and plot the mandlebrot set with the specified 2 dimentional range # compute and plot the mandlebrot set with the specified 2 dimensional range
# info. # info.
def mandelhelp(xmin xmax xstep ymin ymax ystep) def mandelhelp(xmin xmax xstep ymin ymax ystep)
for y = ymin, y &lt; ymax, ystep in ( for y = ymin, y &lt; ymax, ystep in (
@ -631,7 +630,7 @@ def mandelhelp(xmin xmax xstep ymin ymax ystep)
) )
# mandel - This is a convenient helper function for ploting the mandelbrot set # mandel - This is a convenient helper function for ploting the mandelbrot set
# from the specified position with the specified magnification. # from the specified position with the specified Magnification.
def mandel(realstart imagstart realmag imagmag) def mandel(realstart imagstart realmag imagmag)
mandelhelp(realstart, realstart+realmag*78, realmag, mandelhelp(realstart, realstart+realmag*78, realmag,
imagstart, imagstart+imagmag*40, imagmag); imagstart, imagstart+imagmag*40, imagmag);
@ -782,12 +781,12 @@ plot things that are!</p>
<p>With this, we conclude the "adding user-defined operators" chapter of the <p>With this, we conclude the "adding user-defined operators" chapter of the
tutorial. We successfully extended our language with the ability to extend the tutorial. We successfully extended our language with the ability to extend the
language in the library, and showed how this can be used to build a simple but language in the library, and showed how this can be used to build a simple but
interesting end user application in Kaleidoscope. At this point, Kaleidoscope interesting end-user application in Kaleidoscope. At this point, Kaleidoscope
can build a variety of applications that are functional and can call functions can build a variety of applications that are functional and can call functions
with side-effects, but it can't actually define and mutate a variable itself. with side-effects, but it can't actually define and mutate a variable itself.
</p> </p>
<p>Strikingly, lack of this feature is an important limitation for some <p>Strikingly, variable mutation is an important feature of some
languages, and it is not at all obvious how to <a href="LangImpl7.html">add languages, and it is not at all obvious how to <a href="LangImpl7.html">add
support for mutable variables</a> without having to add an "SSA construction" support for mutable variables</a> without having to add an "SSA construction"
phase to your front-end. In the next chapter, we will describe how you can phase to your front-end. In the next chapter, we will describe how you can