# Changeset 9f10d1f2 for doc/proposals/concurrency/text/cforall.tex

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Timestamp:
Nov 23, 2017, 1:31:43 PM (5 years ago)
Branches:
aaron-thesis, arm-eh, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, resolv-new, with_gc
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88ef2af
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07c1e595
Message:

Revised up to chapter three

File:
1 edited

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Unmodified
 r07c1e595 The following is a quick introduction to the \CFA language, specifically tailored to the features needed to support concurrency. \CFA is a extension of ISO-C and therefore supports all of the same paradigms as C. It is a non-object oriented system language, meaning most of the major abstractions have either no runtime overhead or can be opt-out easily. Like C, the basics of \CFA revolve around structures and routines, which are thin abstractions over machine code. The vast majority of the code produced by the \CFA translator respects memory-layouts and calling-conventions laid out by C. Interestingly, while \CFA is not an object-oriented language, lacking the concept of a receiver (e.g., this), it does have some notion of objects\footnote{C defines the term objects as : region of data storage in the execution environment, the contents of which can represent values''\cite[3.15]{C11}}, most importantly construction and destruction of objects. Most of the following code examples can be found on the \CFA website \cite{www-cfa} \CFA is an extension of ISO-C and therefore supports all of the same paradigms as C. It is a non-object-oriented system-language, meaning most of the major abstractions have either no runtime overhead or can be opt-out easily. Like C, the basics of \CFA revolve around structures and routines, which are thin abstractions over machine code. The vast majority of the code produced by the \CFA translator respects memory-layouts and calling-conventions laid out by C. Interestingly, while \CFA is not an object-oriented language, lacking the concept of a receiver (e.g., {\tt this}), it does have some notion of objects\footnote{C defines the term objects as : region of data storage in the execution environment, the contents of which can represent values''~\cite[3.15]{C11}}, most importantly construction and destruction of objects. Most of the following code examples can be found on the \CFA website~\cite{www-cfa} \section{References} *p3   = ...;                                            //change p2 int y, z, & ar[3] = {x, y, z};          //initialize array of references typeof( ar[1]) p;                                       //is int, i.e., the type of referenced object typeof(&ar[1]) q;                                       //is int &, i.e., the type of reference sizeof( ar[1]) == sizeof(int);          //is true, i.e., the size of referenced object sizeof(&ar[1]) == sizeof(int *);        //is true, i.e., the size of a reference typeof( ar[1]) p;                                       //is int, referenced object type typeof(&ar[1]) q;                                       //is int &, reference type sizeof( ar[1]) == sizeof(int);          //is true, referenced object size sizeof(&ar[1]) == sizeof(int *);        //is true, reference size \end{cfacode} The important take away from this code example is that references offer a handle to an object, much like pointers, but which is automatically dereferenced for convenience. The important take away from this code example is that a reference offers a handle to an object, much like a pointer, but which is automatically dereferenced for convenience. \section{Overloading} Another important feature of \CFA is function overloading as in Java and \CC, where routines with the same name are selected based on the number and type of the arguments. As well, \CFA uses the return type as part of the selection criteria, as in Ada\cite{Ada}. For routines with multiple parameters and returns, the selection is complex. Another important feature of \CFA is function overloading as in Java and \CC, where routines with the same name are selected based on the number and type of the arguments. As well, \CFA uses the return type as part of the selection criteria, as in Ada~\cite{Ada}. For routines with multiple parameters and returns, the selection is complex. \begin{cfacode} //selection based on type and number of parameters delete(s);                              //deallocation, call destructor \end{cfacode} Note that like \CC, \CFA introduces \code{new} and \code{delete}, which behave like \code{malloc} and \code{free} in addition to constructing and destructing objects, after calling \code{malloc} and before calling \code{free} respectively. Note that like \CC, \CFA introduces \code{new} and \code{delete}, which behave like \code{malloc} and \code{free} in addition to constructing and destructing objects, after calling \code{malloc} and before calling \code{free}, respectively. \section{Parametric Polymorphism} Routines in \CFA can also be reused for multiple types. This capability is done using the \code{forall} clause which gives \CFA its name. \code{forall} clauses allow separately compiled routines to support generic usage over multiple types. For example, the following sum function works for any type that supports construction from 0 and addition : Routines in \CFA can also be reused for multiple types. This capability is done using the \code{forall} clause, which gives \CFA its name. \code{forall} clauses allow separately compiled routines to support generic usage over multiple types. For example, the following sum function works for any type that supports construction from 0 and addition : \begin{cfacode} //constraint type, 0 and + struct S { int i, j; }; int mem(S & this) with (this)           //with clause i = 1;                                          //this->i j = 2;                                          //this->j i = 1;                                                  //this->i j = 2;                                                  //this->j } int foo() { struct S1 { ... } s1; struct S2 { ... } s2; with (s1)                                       //with statement with (s1)                                               //with statement { //access fields of s1 //without qualification //access fields of s1 without qualification with (s2)                                       //nesting { //access fields of s1 and s2 //without qualification //access fields of s1 and s2 without qualification } } with (s1, s2)                           //scopes open in parallel with (s1, s2)                                   //scopes open in parallel { //access fields of s1 and s2 //without qualification //access fields of s1 and s2 without qualification } } \end{cfacode} \section{otype/dtype} For more information on \CFA see \cite{cforall-ug,rob-thesis,www-cfa}.