False

The arithmetic operations + , - , * , and / take the top two elements from the top of the stack and return there, respectively, the sum, difference, product or quotient. The underscore _ is the unary operation of changing the sign of a number on the top of the stack. Logical operations in FALSE are binary = , > , & , | and the unary operation of logical negation ~ .

Stack operations are quite exotic in FALSE:

• $ - Duplicates the top of the stack (in fort DUP): 0 1 $ → 0 1 1
• % - Deletes the top of the stack (DROP): 0 1% → 0
• \ - Swaps the top two stack elements (SWAP): 0 1 2 \ → 0 2 1
• @ - The cyclic permutation of the top three elements of the stack (ROT): 0 1 2 3 @ → 0 2 3 1
• ø - Copy the nth element of the stack to the top (PICK): 7 8 9 2ø → 7 8 9 7

Variables in FALSE are denoted by a single lowercase Latin letter (az), all variables are global .

To assign a variable a value (taken from the top of the stack), use the colon operation : so 3a: assigns a to 3. To put a variable on the stack, use a semicolon ; .

However, since FALSE is a stack language , variables are rarely needed to store ordinary numeric values. More often they are used as functions - they store lambda expressions , for example:

  [1+] i:

This definition of the function is an increment , and it is given the name i (everything that is between '[' and ']' is the lambda expression). An operation is used to execute a lambda expression ! , if it is stored in a variable, the call takes the form ;! .

In FALSE, there are two control constructs if (denoted ? ) And while - # . Here are examples of their use:

  a; 1 = [3b:]?

If a = 1, set b to 3.

  [a; 1 =] [2f;!] #

While a = 1, apply the function f to the value 2.

Strings in FALSE are all that are enclosed between two quotation marks. " string cannot be put on the stack or stored in a variable, but it can be part of a lambda expression. When a string is executed, it is simply displayed. For example:

  a; 1 = ["unit"]?

To output an integer, use the dot operation . , to display the character - a comma,. To read a character, the ^ operation. Operation ß causes flush of input and output streams ( stdin , stdout ).

Example definition of a factorial function on FALSE:

  [$ 1 = $ [\% 1 \]? ~ [$ 1-f;! *]?] F:

FALSE was implemented as a 1024- byte compiler written in assembly language for 68000 processors and a portable interpreter written in C (an executable version for DOS is available on the site). There is also an interpreter and compiler implementation for 386 DOS on ANSI Forth .

JavaScript implementation of FALSE is also available ^[1] .

There is a functional version of Strictly False written in ML . Another functional extension FALSE is the language F (Functional False) written in K (and the implementation of “pure” FALSE in the same language ^[2] ).

owl

The development of FALSE ideas is owl ( Obfuscated Weird Language ), developed by Antonio Maschio between 2005 and 2006. It differs from FALSE in a larger practical orientation, an expanded set of operations (with a different symbolic designation), the presence of work with strings, etc.

In particular, owl distinguishes between integer variables and function variables. The first are indicated in capital letters, the second lowercase. A comma is used to assign values ​​to both of them, and @ to get a value or start a function. In addition, there is 1 array in the owl virtual machine, the default length of which is 32Kbytes, for which the operations #, and #@ (as well as @, and @@ for functions).

? characters used as if and while ? and ! , these operations distinguish one or two lambda expressions on the stack. So if there are two lambda expressions ? works like if ... then ... else.

The operations ^ and : serve, respectively, for raising to a power and extracting the root. To work with the stack, use the following operations:

The characters of the brackets are used for input-output: ( and ) input and output of the character, { and } - input and output of the string, < - input of numbers (the operation is less absent, $> used instead).

owl also allows you to attach inc files _]inc.owl[ , or run external owl programs _[file.owl] .

In owl (which is more than unusual for esoteric languages), you can even insert comments in the program: lowercase, starting with # , or multi-line, placed between (* and *) . Line comments beginning with the # character allow you to use owl for use in shell scripts .

The owl interpreter is written in C and cross-platform. Under Windows, debugging and profiling capabilities are not supported, the _t function does not work to get the current time.

Now consider the program for outputting primes to false and its translation to owl:

false

  999 9 [1 - $] [\ $ @ $ @ $ @ $ @ \ / * = [1 - $$ [% \ 1 - $ @]? 0 = [\ $. '  , \]?]?] #

owl

  999 9 [1 -%] [$% 2 '% 2'% 2 '% 2' $ / * = [1 - %% [; $ 1-% 2 ']? 0 = [$%. 32) $]? ]?]!

The next example is a factorial calculation program.

  % 0> ~ [?!]? "Factorial of"%. "Is"% 1 = [; 1.] [% 1 - [% 1 = ~] [% 2 '* $ 1 -]!;.]?

1. ↑ javascript FALSE interpreter Archived November 25, 2010.
2. ↑ False! in K

• Wouter's Wiki: False Language - FALSE Homepage
• FALSE Language Guide
• Owl language page