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https://github.com/eudoxia0/magma
Extending C with cmacro
https://github.com/eudoxia0/magma
Last synced: 8 days ago
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Extending C with cmacro
- Host: GitHub
- URL: https://github.com/eudoxia0/magma
- Owner: eudoxia0
- Created: 2014-09-01T21:30:57.000Z (about 10 years ago)
- Default Branch: master
- Last Pushed: 2020-08-04T20:24:13.000Z (over 4 years ago)
- Last Synced: 2024-08-02T15:34:48.182Z (3 months ago)
- Language: C
- Size: 156 KB
- Stars: 328
- Watchers: 10
- Forks: 10
- Open Issues: 1
-
Metadata Files:
- Readme: README.rst
Awesome Lists containing this project
README
################################
Magma: `cmacro`_ extensions to C
################################
.. contents::
:local:
:depth: 2
.. _cmacro: https://github.com/eudoxia0/cmacro
********
Overview
********
C is a tremendously useful language: It compiles everywhere, is generally fast,
has a very long history and a stable standard, and comes with few bedrock
abstractions.
Higher-level languages, like Common Lisp and Haskell, provide excellent
metaprogramming systems and a very expressive type system, but have the cost of
various bedrock abstractions like garbage collection, dynamic typing (In the
case of Lisp), and exception handling.
cmacro provides a middleground: It bridges the power and control of C with the
high-level metaprogramming systems of Lisp. This library uses cmacro to extend
the capabilities of the C language.
*****
Usage
*****
Once you've `built and installed`_ cmacro, simply put these files in a directory
where they can be included by cmacro.
.. _built and installed: https://github.com/eudoxia0/cmacro#installing
*********
Functions
*********
Anonymous Functions
===================
Syntax
------
:code:`lambda (*) -> { * }`
Description
-----------
Defines an anonymous function, returning a pointer to it.
Examples
--------
.. code-block:: c
cmacro_import "fn/lambda.c"
int main() {
int array[] = {423, 61, 957, 133, 969,
829, 821, 390, 704, 596};
qsort(array, 10, sizeof(int),
lambda (const void* a, const void* b) -> int
{ return *(int*)a - *(int*)b; });
for(size_t i = 0; i < 10; i++){
printf("%i ", array[i]);
}
return 0;
}
Lazy Evaluation
===============
Syntax
------
- :code:`delay `
- :code:`force `
Description
-----------
:code:`delay` takes an expression :code:`expr` and delays its computation until
the required time. :code:`force` takes this computation and executes it,
returning its value.
Examples
--------
.. code-block:: c
force (delay 1) == 1;
***********
Type System
***********
Type-Inferenced Variables
=========================
Syntax
------
:code:`var = `
Description
-----------
Defines an implicitly-typed variable :code:`var`, giving it the value
:code:`value`. It is not possible to define a variable without an initial value.
Examples
--------
.. code-block:: c
/* Input */
cmacro_import "type/var.c"
void f() {
var a = 10;
var b = 3.14;
}
/* Output */
void f() {
typeof(10) a = 10;
typeof(3.14) b = 3.14;
/* The above is, in fact, valid */
}
Algebraic Data Types
====================
Syntax
------
Description
-----------
Examples
--------
.. code-block:: c
#include
cmacro_import "type/adt.c"
data Token {
Integer { int i; };
String { char* str; };
}
int main() {
Token a, b;
construct(a, Token -> Integer) { 10 };
construct(b, Token -> String) { "test" };
switch(a.type) {
case TokenInteger:
return a.Integer.i;
break;
case TokenString:
puts(b.String.str);
break;
}
}
Tuples
======
Syntax
------
Description
-----------
Examples
--------
.. code-block:: c
/* Input */
cmacro_import "type/tuple.c"
typedef tup(int, int) pair;
pair divrem(int n, int d) {
return (pair){n/d, n%d};
}
/* Output */
typedef struct { int first; int second; } pair;
pair divrem(int n, int d) {
return (pair){n/d, n%d};
}
****************
Anaphoric Macros
****************
Anaphoric macros store the output of an important argument (Like the condition
in the :code:`if` statement) in a variable named :code:`it` so they can be
accessed in the statement body.
:code:`if`
==========
Syntax
------
- :code:`aif `
- :code:`aif else `
Description
-----------
The value of :code:`cond` is stored in the variable :code:`it`, which is
accessible in the scope of either branch.
Examples
--------
.. code-block:: c
/* Input */
cmacro_import "anaphoric/if.c"
int main() {
aif(5 > 1)
return it;
}
/* Output */
int main() {
typeof(5 > 1) it = 5 > 1;
if(it)
return it;
}
*********
Utilities
*********
:code:`doto`
============
Syntax
------
:code:`doto(obj) { (*);+ }`
Description
-----------
Calls every :code:`fn`, with :code:`obj` appended to the beginning of its
argument list.
Examples
--------
.. code-block:: c
/* Input */
cmacro_import "util/doto.c"
void cancelAccount(Account* account) {
doto(account) {
setBalance(0);
setStatus(DISABLED);
}
}
/* Output */
void cancelAccount(Account* account) {
setBalance(account, 0);
setStatus(account, DISABLED);
}
:code:`with_allocation`
=======================
Syntax
------
- :code:`with_allocation(, ) { * }`
- :code:`with_allocation(, , ) { * }`
Description
-----------
Allocates memory to hold :code:`type`, optionally an array of :code:`type` if
:code:`length` is specified. The pointer is stored in the variable :code:`ptr`
and `free`'d after :code:`body` is executed.
Examples
--------
.. code-block:: c
cmacro_import "util/with_allocation.c"
int main() {
with_allocation(ptr, int, 10) {
size_t i;
for(i = 0; i < 10; i++) {
ptr[i] = i*2;
}
}
with_allocation(p, int) {
*p = 10;
return *p;
}
}
:code:`with_open_file`
======================
Syntax
------
`with_open_file(, , ) { * }`
Description
-----------
Opens :code:`filepath` with mode :code:`mode`, assigning it to the variable
:code:`stream`, then executes body and closes the stream.
Examples
--------
.. code-block:: c
cmacro_import "util/with_open_file.c"
int main() {
with_open_file(file, "README.md", "r") {
printf("The first character in the README is: %c\n",
fgetc(file));
}
return 0;
}
*******
License
*******
Copyright (c) 2014 Fernando Borretti ([email protected])
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.