The Maentwrog Programming Language
This is a rudimentary specification for the Maentwrog programming language.
This information, and the example programs in this distribution, were taken from the esolangs.org wiki page for Maentwrog, written by User:Marinus and (like all esowiki articles) placed in the public domain. Thanks Marinus!
A Maentwrog program consists of a series of words, separated by whitespace. Words can contain any character except whitespace. The way these words are executed depends on the character they begin with.
- A word that consists of digits is taken as an integer and pushed. A
minus sign may be used to make negative numbers, so
-14are words that push 25 and -14 onto the stack. Extra characters at the end of the word are allowed, so
25.14both also push 25.
- A word that isn't a number is treated as either a function or a variable. If the word is defined as a function, it is executed; if it's a variable, its current value is pushed to the stack. Using an undefined word results in an error, though this doesn't stop further execution of the program.
- To define a word as a function, use the syntax
: new-word words to execute ;(as in Forth). Redefining a word is not allowed, and neither are nested function definitions.
- To define a word as a variable, use the syntax
*varname. This must be done before using a variable.
Additionally, words (except number words) can take one of a list of prefixes, changing how the word is executed.
**Prefix** **Action** **Example** **Result** `=` Assign to variable `=foo` A value popped from the stack is assigned to the variable *foo*. `@` If `@bye` Pop value, stop the program (see predefined words) if it isn't 0. `[` While `[xyz` Pop value, if it's not 0 execute word *xyz*, then pop another value and do it again; continue until a 0 is popped. `$` Repeat `$.` Pop value, then output that many values from the stack.
**Word** **Stack effect** **Description** `bye` Stop program immediately. `rem` ... `;` Comment. (Ignore all words between `rem` and `;`.) `:` *word* ... `;` Define a new word. `debug` Turn on debugging (outputs all words executed). `vars` Output a list of currently defined variables and their values. `words` Output a list of currently defined words. `alloc` `n` | `ptr` Allocate memory for *n* C *long*s, returns a pointer. `free` `ptr` | `-` Free memory at pointer. `size` `-` | `n` Push stack size. `dup` `a` | `a a` Duplicate top of stack. `swap` `a b` | `b a` Swap the two topmost stack values. `pop` `a` | `-` Remove top value from stack. `get` `ptr` | `value` Push value at pointer to stack (C `*ptr`). `put` `ptr val` | `-` Store value at pointer (C `*ptr = val`). `rnd` `-` | `n` Push random value. `>` `a b` | `(a>b)` Push 1 if a is greater than b, else 0. `<` `a b` | `(a<b)` Push 1 if a is less than b, else 0. `==` undefined Undefined. `.` `n` | `-` Pop a value, output as integer, adding a newline. `..` `n` | `-` Pop a value, output as an ASCII character. `mod` `a b` | `(a%b)` Modulo. `+` `a b` | `(a+b)` Addition. `-` `a b` | `(a-b)` Subtraction. `*` `a b` | `(a*b)` Multiplication. `/` `a b` | `(a/b)` Division, result is rounded towards 0.