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Notes

Thu, 06 Nov 2025 21:38:58 +0800

Click “…” within and there is “View original page”

Polyglot

Mon, 08 Sep 2025 20:03:11 +0800

While nimpylib(repo) is handy to write Python code in Nim,

what if writing polyglot code, which is runnable in both Nim and Python?

An example (NPython’s test_decimalAndSpace.nim) using such polyglot

How to

We simply write two parts:

run in both languages (thanks to their similar syntax)
snippets run in only one, ignored by another

Many parts of syntax of they two are similar, so we don’t discuss such here

and what’s more important is that how to make some code ignored by specified one language

Cheat Nim to ignore some Python code

Let’s start with the easier one.

#[
<Python code here>
[
]#

Explain

Python regards it as:

Comment [
An empty list literal []
Comment

But in Nim #[ starts a multiline comment and ]# ends it.

Restriction

No more needed to mention but the restriction is cannot contain ]#.

If any, simply rewrite as ] # like [1,2,3] # xxx

Cheat Python to ignore some Nim code

This part is harder.

I’d like to give my solution:

steps

"""\""".`!=`("").assert
<Nim code here>
discard "" != """"_"""

You can also use assert over discard on the last line, which is easier to remember.

Restriction

The only restriction is that cannot contain """.

If any, …consider to split into single line string literals.

Explain

This trick takes advantage of some difference between Nim and Python when parsing multiline string literal node.

Here are their parsing results:

Nim:

assert "" != ('\\' & '"')
<Nim code here>
discard "" != ('\\' & '_')

dumpTree:

  Command
    Ident "assert"
    Infix
      Ident "!="
      StrLit ""
      TripleStrLit  "\\\""  # `\"`
  
  DiscardStmt
    Infix
      Ident "!="
      StrLit ""
      TripleStrLit  "\"_"   # `\_`

Python:

"""\""".`!=`("").assert

discard "" != """ "_" ""

"""\""".`!=`("").assert

discard "" != _"""

'''""".`!=`("").assert

discard "" != _'''

Unicode Space

Sun, 16 Feb 2025 18:17:24 +0800

Introducion

Some online chat clients, like WhatsApp, WeChat and Identity V, reject empty as well as space message.

But once you wanna send blank message, there’s a workaround for WhatsApp and WeChat: just use Unicode Spaces

Workaround

That’s due to WeChat’s isspace only checks ASCII space (U+0020) but not others.

One of the most commonly used is U+2000 ("\u2000" in python):

not worked for Identity V

…

A full list

Unicode	Description	Example
U+0020	Space	[ ]
U+00A0	No-Break Space	[ ]
U+2000	En Quad	[ ]
U+2001	Em Quad	[ ]
U+2002	En Space	[ ]
U+2003	Em Space	[ ]
U+2004	Three-Per-Em Space	[ ]
U+2005	Four-Per-Em Space	[ ]
U+2006	Six-Per-Em Space	[ ]
U+2007	Figure Space	[ ]
U+2008	Punctuation Space	[ ]
U+2009	Thin Space	[ ]
U+200A	Hair Space	[ ]
U+2028	Line Separator	[]
U+205F	Medium Mathematical Space	[ ]
U+3000	Ideographic Space	[　]

ref https://emptycharacter.com/

Hello2025

Tue, 28 Jan 2025 23:48:42 +0800

Hello New Year 2025

Happy China New Year!

Everyone!

In my opinion, the very part of this new year to commemorate is “It’s Python Year”

Yep. Have fun.

Hello

Mon, 13 Jan 2025 04:53:05 +0800

Hello, Welcome

Welcome to u!

Here’s my blog website, where I’d like to share somthing about my daily experiement as well as my notes.