metmice

A programming language.

How does the language works ?

Basicly, it is half stack based, and half not.

There are three stacks :

• the first one is for the output
• the second one is for computing
• the third one is for interracting with the system

There are also two types of computing : rpn and normal. The rpn stands for reversed polish numeration. Basicly, you would in a first time give the two arguments and the the operator. Example : 1 2 + returns 3.

For the syntax, there is one rule to follow : THERE MUST BE SEMICOLONS AT THE END OF EACH EXPRESSIONS.

Example :

1 + 2;

or

if(true)
{
    push 1 "It is indeed";
};

The types

In Metmice, there are 6 major types :

• string
• int (integers)
• floats
• bools
• list
• none

However, you can define you own types.

For now, you can't convert types. It means that during you program, a string stays a string, a float stays a float etc... As well as in a calculation, you can't use an operator between two differents types.

The operators

See all the operators

operator +	bool	string	int	float	list	others	description
bool
string
int			x				adds two integers
float				x			adds two floats
list	x	x	x	x	x	x	adds the element at the end of the list
others

operator -	bool	string	int	float	list	others	description
bool
string		x					adds two strings (example : "a" + "b" gives "ab")
int			x				substract two integers
float				x			substract two floats
list
others

operator *	bool	string	int	float	list	others	description
bool
string
int			x				multiplies two integers
float				x			multiplies two floats
list			x				get the value of the list at the given index
others

operator /	bool	string	int	float	list	others	description
bool
string
int			x				divides two integers
float				x			divides two floats
list
others

operator //	bool	string	int	float	list	others	description
bool
string
int			x				operates an euclidean division on two integers
float				x			operates an euclidean division on two floats
list
others

operator %	bool	string	int	float	list	others	description
bool
string
int			x				operates a modulo on two integers
float				x			operates a modulo on two floats
list
others

operator ^	bool	string	int	float	list	others	description
bool
string
int			x				operates a power on an integer to an other
float				x			operates a power on a float to an other
list
others

operator =	bool	string	int	float	list	others	description
bool	x	x	x	x	x	x	Tests if the two values are the same. Returns a bool
string	x	x	x	x	x	x
int	x	x	x	x	x	x
float	x	x	x	x	x	x
list	x	x	x	x	x	x
others	x	x	x	x	x	x

operator >	bool	string	int	float	list	others	description
bool
string
int			x				tests if an integer is greater than an other
float				x			tests if a float is greater that an other
list
others

operator <	bool	string	int	float	list	others	description
bool
string
int			x				tests if an integer is lower than an other
float				x			tests if a float is lower that an other
list
others

Variables

Now you know how to operate operations in Metmice.

But maybe you wants to define a variable ...

As a matter of fact, it is really simple :

all you need to do is add an -> (asignement operator) and a variable name.

For instance, to define a variable called 'toto' which contains the value "Hello World!" :

"Hello World!" -> toto;

Then you can reuse the variable whenever you wants :

push 1 toto;

(it prints the value of 'toto', here "Hello World!")

They are two types of variables local and global. Global variables are the one you defines outside a function, and local is the one you will define - you've guess it - inside a function.

Functions

The functions declaration goes like this : function_name(arg1, arg2)[none]{ your code goes there};

For example :

add(a, b)[none]
{
   return a + b;
};

Then to execute the function you place an exclamation point before the function name ! and then you pass the arguments between parentethis.

Example :

!add(1, 3);

!add(5, 6) -> variable;

Keywords

There are a lot of keywords :

• return => returns the value in a function

  toto(x)[none]
  {
    return x + 1;
  };
  

• break => breaks the loop

  for(i, 0, 10)
  {
    break;
  }
  

• push => pushes the second argument on a given stack number

  push 1 "Hello World! \n";
  

• include => include the file given as a string

  include "std.mtmc";
  

• type => pushes on the compute stack the type of a given value, as a string

  type "test";
  

• global => globalize a variable in a function (not recomended)

  toto(x)[none]
  {
    x + 1 -> y;
    global y;
  }
  !print(y); 
  

• length => pushes on the compute stack the lenght of a list

  length [1, 2, 3];
  !print( + 0);
  

• pop => pops a given index in a list

  [1, 2, 3] -> list;
  pop -1 list;
  

• operator => binds an operator with a function

  operator "&" "!and";
  

Beware, you can not use all the keywords wherever you wants !

Loops

They are two types of loops : for loops and while loops

The for loops takes 3 arguments : the name of the variable, the starting point and the ending point. Both starting and ending points must be integers.

Example :

for(i, 0, 10)
{
  push 1 i;
  push 1 "\n";
};

The while loop takes as an argument a boolean. It will iterate while the boolean is not 'false'.

Example :

0 -> i;
while (i < 0)
{
  push 1 i;
  i + 1 -> i;
};

Structures

In metmice, you can define a structure using struct.

for example :

struct t
{
  0 -> sum;
  get_sum(self)[none]
  {
    return self.sum;
  };
};

Inside the curly brackets, you can define some attributes (variable that are only for a given object) and some function attributes. You can then create an object with the type you precedently difined :

!t() -> test;

In order to access one of its atribute : use a point between the variable name and the attribute name :

push 1 test.sum;

To execute one of its function attribute, use an exclamation point followed by the variable name and the function name and the arguments :

!test.get_type();

You might notice that the object is passed as an argument (here self).

How to execute you code

In bash (Linux) and Zsh :

metmice-x.x your_program_name.mtmc [-options]

Options are :

• --strict_disabled or -S to disable a strict analyse of the code
• --debug_disabled or -d to not debug the code
• --ast_show or -A to show the abstract syntax tree
• --clear_stack_disabled or -c to desable the compute stack clearing
• --help or -h to show the help message
• --print_full_error or -e to print the full error calling stack

How to start a new program

The first and most recommended thing to do when you create a ".mtmc" file is to include the standard librairie. To do so, just write at the begining of your file : include "./path/to/the/file/std.mtmc

With that done, you can now use all the functions you will need !