We can do better: FALSE

Question

The interpreter executable for FALSE is 1020 bytes large. I think we can do better than THIS:

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Challenge

Write a FALSE interpreter in any language (doesn't have to be an executable!). As usual, shortest bytes wins. Make sure to try to get it under 1020 though :)

Language Specs

Literals

• 123 put integer onto the stack
• 'c put character code onto the stack

Stack

• $ DUP
• % DROP
• \ SWAP
• @ ROT
• ø PICK (dup the nth stack item)

Arithmetic

• + ADD
• - SUBTRACT
• * MULTIPLY
• / DIVIDE
• _ negate (negative numbers are entered 123_)
• & bitwise AND
• | bitwise OR
• ~ bitwise NOT

Comparison (false is zero, true is all bits set (-1 or ~0) so that bitwise operators may be used)

• > greater than
• = equals

Lambdas and flow control (tests are for non-zero)

• [...] define and put a lambda onto the stack
• ! execute lambda
• ? conditional execute: condition[true]?.
  • An if-else can be expressed as: condition$[\true\]?~[false]?
• # while loop: [condition][body]#

Names

• a-z put a reference to one of the 26 available variables onto the stack
• : store into a variable
• ; fetch from a variable

Input and Output

• ^ read a character (-1 for end-of-input)
• , write a character
• "string" write a string (may contain embedded newlines)
• . write top of stack as a decimal integer
• ß flush buffered input/output

Other

• {...} comment
• whitespace is ignored, may be needed to separate consecutive integers

Examples

Copy file:

{ copy.f: copy file. usage: copy < infile > outfile  }

ß[^$1_=~][,]#

Factorial:

{ factorial program in false! }

[$1=~[$1-f;!*]?]f:          { fac() in false }

"calculate the factorial of [1..8]: "
ß^ß'0-$$0>~\8>|$
"result: "
~[\f;!.]?
["illegal input!"]?"
"

Primes to 100:

{ writes all prime numbers between 0 and 100 }

99 9[1-$][\$@$@$@$@\/*=[1-$$[%\1-$@]?0=[\$.' ,\]?]?]#