Comfort Lang

Comfort Lang is an early-stage progressively-evolving imperative programming language. Single-file interpreter, Python 3.6+ only, MIT-licensed. It focuses on a clean and pleasant interactive programming experience.

Comfort Lang is not a simplified Python; it re-thinks human-computer interaction. Python is used only as an extension ecosystem. Version: v1.0.1

GitHub Repository

Tip: In REPL mode, type variables or expressions and press enter. Results are printed automatically; no print function needed.

Quick Start

Clone repository and launch interpreter:

git clone https://github.com/dxiangwiki/comfort-lang.git
cd comfort-lang
python comfort_lang.py

Prompt > means you are inside Comfort Lang REPL. Type exit to quit.

Variable declaration def

Use def to declare multiple variables in batch.

Declared via def but unassigned: returns [None]
Never-declared non-existent variable: returns [null]

> def a b c
[success]
> a
[None]
> d
[null]

Batch assignment

Comma-separated batch assignment. Commas inside strings or brackets will not be incorrectly split. Escape quotes are supported.

> a=10,b=20
[success]
> a
[10]
> a + b
[30]

> s="he said \"hello\""
[success]
> s
[he said "hello"]

Function definition

Arrow syntax for top-level expression-based functions: function name=(args)=>expression

> function add=(x,y)=>x+y
[success]
> add(a,b)
[30]
> add(50,60)
[110]

# zero-argument function
> function hello=()=>999
[success]
> hello()
[999]

Function environment snapshot

When defining a function, a deep-copy snapshot of current global environment is created. Functions capture variable states at definition time.

Later re-assignments or modifications to mutable objects (list / dict) will not affect already-created functions. Nested-function support will come in future releases.

> def arr
[success]
> arr=[1,2,3]
[success]
> function get_arr=()=>arr
[success]
> get_arr()
[[1, 2, 3]]

> arr.append(99)
[None]
> get_arr()
[[1, 2, 3]]

Full REPL demo

> def a b
[success]
> function add=(x,y)=>x+y
[success]
> a=100,b=200
[success]
> a
[100]
> b
[200]
> a + b
[300]
> add(a,b)
[300]
> exit
👋 Thank you for using Comfort Lang!

Status markers

[success]: Statement executed successfully
[None]: Variable declared but not assigned; some built-in methods return empty result
[null]: Variable does not exist / never declared
[error]: Syntax error or runtime exception

Built-in functions

Safe Python built-ins can be called directly without import. Dangerous system-related functions are blocked.

> abs(-99)
[99]
> len("Comfort Lang")
[12]
> max(10,20,99)
[99]
> sum([1,2,3,4,5])
[15]

Current Limitations

⚠️ Security Notice

✅ Safe for local use: Download and run REPL on your own device. You may clone, Star, Fork, share and iterate publicly.

❌ Not recommended to deploy as public online backend service: The interpreter uses Python eval for expression evaluation. Even with a dangerous-function blocklist, escape risks from untrusted external input cannot be fully eliminated.

This is an early-stage progressively-iterated project, targeting local interactive development scenarios only. Do not treat it as an online-ready service component. More syntax features will be added in future versions.

function only supports top-level definitions. Nested function definitions inside expressions are unsupported; full lexical closure is not implemented yet.
Only REPL interactive mode is available; loading .cl script files is not supported.
No block syntax {}, no if / while statements. Only expression evaluation works currently.
Future releases will add statement blocks, conditionals, loops and script-file loading.