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[comments in square brackets]

[preprocessor directives]
#INCLUDE 'math.halk';                                    [looks for a 'math.halk' file in the cwd, then ~/halk/include]
#INCLUDE 'io' AS '';                                     [bring everything in 'io' into global scope]


let.hello -> 'hello, ';                                  [variables must be given a value at declaration]

let.PI => math/PI;                                       [namespaces are accessed with a '/']
                                                         [constants are denoted with a '=>']

fn.greeting,to -> {                                      [functions defined with: `fn.<name>,<argument>,..., -> {<body>};`] 
   let.message -> strcat.hello,to;                       [functions are right-associative]

   stdo.message;                                         [since 'io' was brought into global scope, we
                                                         do not prefix it with a namespace/]
};

fn.sum_all._ -> {                                        [variadic functions are possible with the reserved '_' argument,
                                                         which is treated as an array]
   return.foldl.+,0,_;  
};

fn.fibonacci.n -> {
   if.or.(num=?.n, 0), (num=?.n, 1) -> {                 [functions ending in '?' should be predicates]
      return.1;
   };
   return.+.(fibonacci. -.n, 1), (fibonacci. -.n, 2);    [parens can be used to group function application]
};

fn.main -> {   [where our code will begin executing]
   greeting.[comments can be placed *anywhere*]"world.";
   exit.0;                                               [exit with code 0 for success]
};