Synposis

LambdaPP is a preprocessor for giving you anonymous functions in C.

Examples

// for an example the table consists of a string keyed (room) of occupants
// stored in a linked list.
hashtable_t *table;
hashtable_foreach(table,
    lambda void(list_t *list) {
        list_foreach(list,
            lambda void(const char *occupant) {
                printf(">> %s\n", occupant);
            }
        );
    }
);

Closures are not supported by this system. It's important to note these are not nested functions or blocks, for information on these please see the following links.

Nested functions

Blocks

This is a source translation that produces global functions and replaces instances of the lambda with the literal.

How it works

Given a lambda, a static function is created. The scope which implements the lambda is replaced with a reference to the static function by taking it's address.

Example

(lambda void(void) { printf("Hello world"); })();

Would be translated to

static void lambda_0(void);
(&lambda_0)();
static void lambda_0(void) { printf("Hello world"); }

To better see how it works, here's the original example expanded:

hashtable_t *table;
static void lambda_0(list_t *list);
hashtable_foreach(table, &lambda_0);
static void lambda_1(const char *occupant);
static void lambda_0(list_t *list) {
    list_foreach(list, &lambda_1);
}
static void lambda_1(const char *occupant) {
    printf(">> %s\n", occupant);
}

Diagnostics

LambdaPP inserts #file and #line directives into the source code such that compiler diagnostics will still work.