diff -r 65d18005d802 -r 9e888d60d3e5 doc-src/TutorialI/CodeGen/document/CodeGen.tex --- a/doc-src/TutorialI/CodeGen/document/CodeGen.tex Fri Jan 05 18:32:33 2001 +0100 +++ b/doc-src/TutorialI/CodeGen/document/CodeGen.tex Fri Jan 05 18:32:57 2001 +0100 @@ -8,7 +8,7 @@ \begin{isamarkuptext}% \label{sec:ExprCompiler} The task is to develop a compiler from a generic type of expressions (built -up from variables, constants and binary operations) to a stack machine. This +from variables, constants and binary operations) to a stack machine. This generic type of expressions is a generalization of the boolean expressions in \S\ref{sec:boolex}. This time we do not commit ourselves to a particular type of variables or values but make them type parameters. Neither is there @@ -24,7 +24,7 @@ The three constructors represent constants, variables and the application of a binary operation to two subexpressions. -The value of an expression w.r.t.\ an environment that maps variables to +The value of an expression with respect to an environment that maps variables to values is easily defined:% \end{isamarkuptext}% \isacommand{consts}\ value\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequote}{\isacharparenleft}{\isacharprime}a{\isacharcomma}{\isacharprime}v{\isacharparenright}expr\ {\isasymRightarrow}\ {\isacharparenleft}{\isacharprime}a\ {\isasymRightarrow}\ {\isacharprime}v{\isacharparenright}\ {\isasymRightarrow}\ {\isacharprime}v{\isachardoublequote}\isanewline @@ -34,7 +34,7 @@ {\isachardoublequote}value\ {\isacharparenleft}Bex\ f\ e{\isadigit{1}}\ e{\isadigit{2}}{\isacharparenright}\ env\ {\isacharequal}\ f\ {\isacharparenleft}value\ e{\isadigit{1}}\ env{\isacharparenright}\ {\isacharparenleft}value\ e{\isadigit{2}}\ env{\isacharparenright}{\isachardoublequote}% \begin{isamarkuptext}% The stack machine has three instructions: load a constant value onto the -stack, load the contents of a certain address onto the stack, and apply a +stack, load the contents of an address onto the stack, and apply a binary operation to the two topmost elements of the stack, replacing them by the result. As for \isa{expr}, addresses and values are type parameters:% \end{isamarkuptext}% @@ -62,12 +62,12 @@ return the first element and the remainder of a list. Because all functions are total, \isa{hd} is defined even for the empty list, although we do not know what the result is. Thus our model of the -machine always terminates properly, although the above definition does not +machine always terminates properly, although the definition above does not tell us much about the result in situations where \isa{Apply} was executed with fewer than two elements on the stack. The compiler is a function from expressions to a list of instructions. Its -definition is pretty much obvious:% +definition is obvious:% \end{isamarkuptext}% \isacommand{consts}\ comp\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequote}{\isacharparenleft}{\isacharprime}a{\isacharcomma}{\isacharprime}v{\isacharparenright}expr\ {\isasymRightarrow}\ {\isacharparenleft}{\isacharprime}a{\isacharcomma}{\isacharprime}v{\isacharparenright}instr\ list{\isachardoublequote}\isanewline \isacommand{primrec}\isanewline