Sigi

A pure symbolic stack language that compiles to C.

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

All syntax is symbolic. No alphanumeric keywords.

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Installation

pip install -e .

This installs the sigic compiler.

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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

# Debug: show AST
sigic hello.si --emit-ast

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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

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Examples

Hello World

"Hello, World!\n"

Arithmetic

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

Stack operations

!5 @ + |      \ 10 (DUP + ADD)
!1 !2 # | |   \ 2 1 (SWAP)

Variables

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

Functions

{0 "Hi\n"}     \ define fn 0
{1 !42 |}      \ define fn 1
(0)            \ call fn 0
(1)            \ call fn 1

Control flow

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

While loops

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

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Design

Sigi is deliberately minimal. Every operation is a single character. There are no reserved words—only punctuation.

The language is stack-based with postfix notation, making parsing trivial.

Inspired by Forth, Joy, and other concatenative languages.