Sigi

Sigi is an esoteric stack language where all syntax consists of symbols and punctuation. No alphanumeric keywords anywhere.

Character set: !@#$%^&*()-+=[]{}|;:'",.<>/?\~ plus digits 0-9

Installation

pip install -e .

This installs the sigic compiler.

Usage

# Compile to C
sigic hello.si -o hello.c

# Compile and run immediately
sigic hello.si --run

# Debug: show tokens
sigic hello.si --emit-tokens

Symbol reference

Symbol	Name	Effect
!N	PUSH	Push number N (int or float)
@	DUP	Duplicate top of stack
#	SWAP	Swap top two elements
$	DROP	Discard top of stack
+	ADD	Pop b, pop a → push a + b
-	SUB	Pop b, pop a → push a - b
*	MUL	Pop b, pop a → push a * b
/	DIV	Pop b, pop a → push a / b
%	MOD	Pop b, pop a → push fmod(a, b)
=	EQ	Pop b, pop a → push 1 if equal, else 0
<	LT	Pop b, pop a → push 1 if a < b
>	GT	Pop b, pop a → push 1 if a > b
~	NOT	Pop a → push 1 if zero, else 0
`	`	PRINT
^	PRINTC	Pop and print as character
?	INPUT	Read number from stdin
:	STORE	Pop address, pop value → store to var
<n>	LOAD	Push value of variable n (digits 0-99)
[ body ]	WHILE	Loop while stack top is nonzero
{ then ; else }	IF-ELSE	Pop condition, execute then or else
{N body }	FUNC	Define function N (0-99)
(N)	CALL	Call function N
"text"	STRING	Print characters
'x	CHAR	Push character code
\	COMMENT	Line comment (rest of line ignored)

Data model

• All values are 64-bit IEEE 754 doubles
• Stack depth: 1000 by default
• 100 variables: vars[0]–vars[99]

Examples

Hello World

"Hello, World!\n"

Arithmetic

!3 !4 + |     \ prints 7
!10 !3 - |    \ prints 7
!4 !5 * |     \ prints 20

Stack operations

!5 @ + |      \ 10 (DUP then ADD)
!1 !2 # | |   \ 2 then 1 (SWAP)
!1 !2 !3 $ | | |  \ 2 then 1 (DROP)

Variables

!42 !0 :       \ store 42 in var 0
0 |            \ print 42

!7 !1 :        \ store 7 in var 1
1 !2 * !1 :    \ var[1] *= 2

Functions

{0 "Hi\n"}     \ define function 0
{1 !42 |}      \ define function 1

(0)            \ calls fn 0
(1)            \ calls fn 1

Control flow

!1 { "yes" ; "no" }    \ prints "yes"
!0 { "yes" ; "no" }    \ prints "no"

While loops

!5 [ @ | !1 - ] $      \ prints 5 4 3 2 1

Loop semantics: peek at stack top. If zero, exit. Otherwise execute body. Body must leave updated counter on stack.

Factorial

!5 !4 * !3 * !2 * !1 * |    \ prints 120

Project layout

sigi/
  lexer.py      – tokeniser
  parser.py     – parser → opcodes
  codegen_c.py  – C code generator
examples/       – sample .si programs

Licence

AGPL 3.0