Macro proposal II

macro2.c

// Switch
macro char * @foo(&x) {
  $switch (@typeof(x)) {
    $case int: return "int";
    $case float: return "float";
    $default: return "???";
  } 
}

char *x = @foo(10); // char *x = "int";
char *y = @foo(1.1); // char *y = "float";

// If-else
macro char* @foo2($x) {
  $if ($x > 10) {
    return "too_big";
  } $else {
    return "ok";
  }
}

char *x = @foo2(5); // char *x = "ok";
char *y = @foo2(20); // char *y = "too_big";

// For
macro float @foo3($x) {
  float $f = 0;
  $for (int $i = 0; $i < $x; $i++) {
    $f += ($i + 1) * ($i + 1);
  }
  return $f;
}

float x = @foo3(3); // float x = 14.0

// Generating structures (aka poor man's templates)
// ` ` makes pure text insert
macro @hash_define($type) {
  $struct_name = $type + "Hash";
  typedef struct {
    $type value;
    int hash;
  } `$struct_name`;
  
  $struct_name_map = $struct_name + "Map";
  typedef struct { 
    `$struct_name` *entries;
    size_t size;
  } `$struct_name_map`;
    
  `$struct_name_map`* `$struct_name_map + "_create()"` {
     `$struct_name_map` *new = malloc(@sizeof(`$struct_name_map`));
     new->size = 0;
     new->entries = NULL;
     return new;
  }
}

@hash_define(Foo); // =>

typedef struct {
  Foo value;
  int hash;
} FooHash;

typedef struct {
  FooHash *entries;
  size_t size;
} FooHashMap;
    
FooHashMap *FooHashMap_create() {
  FooHashMap *new = malloc(@sizeof(Foo));
  new->size = 0;
  new->entries = NULL;
  return new;
}