slang

Slang is an interpreted stack-based "programming language".

This project is a pathetic parody of Porth by Alexey Kutepov.

Examples

Hello, World:

include std.io

macro main using std.io namespaces
    "Hello, world!\n" popln!
end

Simple program that prints numbers from 1 to 15 in an ascending order:

include std.io
const CAP 15
macro main using std.io namespaces
    0
    cycle:
        ++ println! 
        dup CAP! = not
        if cycle~ fi
    drop
end

Quick start

Slang is an interpreted "programming language" so you need to configure interpretator before using it. Right now you just need to go to src/pyslang and change LIBS_PATH const to where you have slang std library. Maybe i'll create a configuration file later.

After you've done configuration, just run pyslang run [path to program].

Language reference

Literals

Integer

Integer is a sequence of decimal digits that optionally starts with dash (-) to indicate a negative integer. When an integer is encountered it is pushed onto the stack.

Example:

5 10 +

This code pushes 5 and 10 onto the stack and then finds their sum with + operation.

String

String is a sequence of bytes between two ". No newlines are allowed, as Python supports unicode, slang does too.

Allowed escapes:

\n - new line
\r - carriage return
\" - double quote

When the interpretator encouters a string it is pushed onto the stack.

Example:

include std.io

macro main using std.io namespaces
   "Hello, world!" popln!
end

The std.io.popln macro expects any kind of value on the stack prints it and drops it. (<=> std.io.println! drop)

Other

There are other types supported, such as float and bool. Actually, slang can work with any python type though it is not convinient as there's no suitable tools.

Intrinsics (Built-in words)

Stack manipulation

Name	Signature	Description
`dup`	`a -- a a`	duplicate an element on top of the stack
`swap`	`a b -- b a`	swap 2 elements on the top of the stack
`drop`	`a b -- a`	drops the top element of the stack
`rot`	`a b c -- c b a`	rotate the top three stack elements
`size`	`a -- a s`	pushes size of stack (int) on top of it

Comparison

Name	Signature	Description
`=`	`a b -- [a == b : bool]`	checks if two elements on top of the stack are equal.
`!=`	`a b -- [a != b : bool]`	checks if two elements on top of the stack are not equal.
`>`	`a b -- [a > b : bool]`	applies the greater comparison on top two elements.
`<`	`a b -- [a < b : bool]`	applies the less comparison on top two elements.
`>=`	`a b -- [a >= b : bool]`	applies the greater or equal comparison on top two elements
`<=`	`a b -- [a <= b : bool]`	applies the greater or equal comparison on top two elements.

Communication with Python

Name	Signature	Description
`pyimport`	`b [a: string] -- b`	imports a python library
`pycall`	`b [a: string] -- b [c: Object]`	calls a python method

There are some more but I'm tired of that.

Control Flow

if-condition

// -- snip --
<condition> if
    <body>
fi
// -- snip --

while-loop

// -- snip --
<start condition> while
    ...contents
<continue condition> do
// -- snip --

Include

// -- snip --
include package.file
// -- snip --

That code will include file from path {LIBS_PATH}/package/file.slang

Macros

// -- snip --
macro print-hello-world
    "Hello, world!\n" std.io.popln!
end
// -- snip --
macro main
    print-hello-world!
end

Constants

// -- snip --
const ONEHUNDRED 100
// -- snip --

rastsislaux/slang