README.md

ts-stable

STABLE programming language in Typescript

STABLE is an extremely minimalistic "Forth-like" (but not Forth) language by Sandor Schneider. Originally in C, I have ported it to Typescript to explore what can be done with the one of the world's smallest viable programming languages.

STABLE stands for STAck Bytecode Language & Engine and the original implementation is only about 233 lines of formatted C code and much shorter if all the whitespace is removed.

Go here to see a fully working version of STABLE in your browser.

Glossary

Arithmetic

opcode	stack effects	description
+	(a b -- a+b)	addition
-	(a b -- a-b)	subtraction
*	(a b -- a*b)	multiply
/	(a b -- a/b)	division
%	(a b -- a%b)	modulo (division remainder)
_	(n -- -n)	negate

Bit manipulation

opcode	stack effects	description
&	(a b -- a&b)	32 bits and
|	(a b -- a | b)	32 bits or
~	(n -- n')	not, all bits invertsed (0=>1 1=>0)

Stack

opcode	stack effects	description
#	(a -- a a)	duplicate top of stack
\	(a b -- a)	drop top of stack
$	(a b -- b a)	swap top of stack
@	(a b -- a b a)	(over) copy next of stack on top

Register

opcode	stack effects	description
x	( -- )	select register x (x: a..z)
;	( -- value)	fetch from selected register
:	( value --)	store into selected register
?	( -- value)	selected register contains an address. Fetch value from there
!	( value --)	selected register contains an address. Store value there.
-	( -- )	immediately after register, increment content by 1
*	( -- )	immediately after register, decrement content by 1

Functions

opcode	stack effects	description
{X	( -- )	start function definition for function X (A..Z)
}	( -- )	end of function definition
X	( -- )	call function X (A..Z)

I/O

opcode	stack effects	description
.	(value -- )	display value as decimal number on stdout
,	(value -- )	send value to terminal, 27 is ESC, 10 is newline, etc.
^	( -- key)	read key from terminal, don't wait for newline.
"	( -- )	read string until next '"' put it on stdout
0..9	( -- value)	scan decimal number until non digit. to push two values on stack separate those by space (4711 3333). to enter negative numbers call _ (negate) after the number
0..9.0	( -- value)	to enter float numbers digits must contain one '.' (only available if float module is active, see 0`)

Conditionals

opcode	stack effects	description
<	(a b -- f)	true (-1) if b is < a, false (0) otherwise
>	(a b -- f)	true (-1) if b is > a, false (0) otherwise
=	(a b -- f)	true (-1) if a is equal to b, false (0) otherwise
(	(f -- )	if f is true, execute content until ), if false skip code until ')'
[	(f -- f)	begin while loop only if f is true. keep flag on stack if f is false, skip code until ']'
]	(f --)	repeat the loop if f is true. If f is false continue with code after ']'