An implementation of the herbert language

A simple language which was created for the purpose of a puzzle/riddle game whit the same name. You can find more about Herbert here.

Install

$ pip install herbert

Run

$ herbert code.h
sssrrr

content of the code.h file

# code.h
f:rrr
sssf

Usage

As an output the language will generate a chain combined of s, r, l, eg sssrrssllss

Where:

s - stands for straight This makes the robot move straight ahead;
l - stands for left) This makes the robot turns to its left;
r - stands for right) This makes the robot turns to its right.

Each of this steps is responsible of changing state of the game character.

For example the program sssslssssr means "move four units straight, then turn to your left, move four units straight, then turn right." Of course, any level may be solved just with these.

But the real objective of the game, is to write small programs (the smallest possible). In order to do that language provides functions.

Basics

To call the same sequence of steps more than once. Functions are just a way to group a sequence of commands that you can reuse many times. For example, here is a program that creates a function:

f:ssss
flfr

The first line defines the function. Function have names consisting of one lower case letter (here we named it f), after the function name comes a :(colon) then the instructions (called the function body, here it is ssss), and a new line terminates the definition. Now you can "call" the function simply using its name as a new instruction, that is flfr is now equivalent to sssslssssr. Note that you cannot name a function r, s or l since those three letters are reserved for the three primitives of h.

Function bodies can contain any instructions even other function calls. For example:

f:ssss
q:flfr
q

Recursion

This program is equivalent to the above. Note how it defines two functions (f and q), and how the second one calls the first. Functions can even call themselves, this is called recursion:

f:sf
f

In this program we define a function that executes an s, and then calls itself which executes s, which calls f again .... etc. This means that, when executing the f the robot well keep moving forward infinitely.

Numeric arguments

Functions can take arguments to control their behavior. There are two types of arguments: instruction arguments, and numeric arguments. Here is an example of numeric arguments:

f(A):ssslf(A-1)
f(4)

The 'f' function takes a single argument (called 'A'). Argument names must be one upper case letter. When using such a function you must append the parameters you want to pass (surrounded by round brackets) to the function name. In the example, we passed 5 as the value of A. The f function will execute sssl and then calls itself with a parameter of A-1. That is, calling f(4) will call f(3), which will call f(2), which will call f(1). Calling f(1) will result in the execution of sssl but f(0) will never be called. This is because if one of the numeric parameters to a function call is zero or less, the call is not performed at all. In summary calling f(4) will result in ssslssslssslsssl. You can use any expression (for numeric parameters) involving constants (such as 1, -5, ...), argument names (A,B,..), plus sign + and minus sign -.

Step arguments

There another kind of arguments called instruction arguments. Here is an example:

f(B):Bf(Bs)
f(l)

Here the parameter passed to f is not supposed to be a number but an instruction sequence (like ssslssl). In order to invoke the instuction sequence passed as an argument simply use the argument name as a function call (as in f(A):sAlA). In the above example, f is called with a single l instruction as a parameter. f then invokes/executes its parameter, before calling itself with the same parameter to which it appends a new s. In the end this will result in the following (infinit) instruction sequence: llslsslssslsssslssssslssssss...

Mixing arguments

Of course, you can have more than one argument and you can mix both types within the same function:

f(A, B):Arf(sA, B-1)

Now f(s, 5) will result in srssrsssrssssrsssssr

That's it! You know all you need to know to write "h" programs.

Solving Levels

To solve level in the text mode, you will need few things:

Create the level file

Or just use the one bellow

{
	"content": [
		".........",
		".........",
		"..@.2.@..",
		"....^....",
		"..*^^^*..",
		"....^....",
		"..@.*.@..",
		".........",
		"........."
	],
	"limits": [
		30,
		25,
		10
	],
	"name": "Level 1",
	"key": "0e91d682d"
}

A brief introduction what is what here.

* - it's a star, the main goal for the programm is collect them all
. - just a space, you can move there
0, 1, 2, 3 - starting point, depending on the number it faces 'player' towards: 0 up, 1 right, 2 down, 3 left

Crate the code file

f:slsrsls
rfff

Use your imagination and run

$ herbert code.h level.json

= Translated =
ssrssrssssrssssrssss

= Level =
walk: ssrssrssssrssssrssss
position: x=1 y=1
solved: ★ ★ 
length: 22

Herbert Game

I'm in progress of implementing a new version of Herbert game ;) Stay tuned.

Developer preview is available here http://xando.webfactional.com/

xando / herbert