Implement a set of built-in methods to be used on strings/integers/....

Since we now have the Attribute visitor in AST->ASR, we should start implementing the set of built-in methods to be used on strings, integers, lists, dictionaries, etc.

Here's a list of those operating on strings: https://www.w3schools.com/python/python_ref_string.asp
And one can navigate on the left for other types.

Let's start with something easy, like bit_length for integers:

>>> num = 9
>>> num.bit_length()
4

Yes. Implement them as _lpython_bit_length(i: i32), make the AST to ASR insert these in. Those that can be implemented in Python should be. Otherwise just do the declaration and the backend (ASR->LLVM) has to implement them.

We can try this (or something similar):

>>> def _lpython_bit_length(i: int) -> int:
...   x: str
...   x = bin(i)
...   if i == 0: return 0
...   elif i < 0: x = x[3:]
...   else: x = x[2:]
...
...   return len(x)
...
>>> all(_lpython_bit_length(i) == i.bit_length() for i in range(-1000, 1000))
True
>>>

Just to make the design cleaner and not just put everything into Attribute, I suggest creating a map something similar to intrinsic procedures, where we can directly look for the methods (for example, maybe we can map list.append to a string list%append and use this converted string to find the appropriate function.)

We should try to systematically manage these methods, and at the same time keep the complexity low at the C++ level. Having some kind of a map like we do for comptime_eval is fine I think.

Please, could someone possibly share if the built in methods need to be implemented as compile time functions (like here ) or runtime functions (like here) or both?

@Shaikh-Ubaid

@Shaikh-Ubaid every intrinsic function has both compile time and runtime implementation. Sorry for my late reply, I was just going through my notifications and noticed your question.

Got it. Thank you for the clarification!

Add the function _lpython_bit_length into src/runtime/lpython_builtin.py, then in AST->ASR, when you encounter num.bit_length(), simply call this function.

@Abdelrahman-Kh-Fouad -- are you working on this?

@Abdelrahman-Kh-Fouad -- are you working on this?

yes i will, after str() casting.

Do we still have any methods left to implement? I would like to implement.

@navneet1v

@navneet1v thanks for your interest!

If I am not mistaken, all the methods on integer that we implemented so far are here:

lpython/src/lpython/semantics/python_ast_to_asr.cpp

Line 4728 in b3534ff

} else if (AST::is_a<AST::ConstantInt_t>(*at->m_value)) {

, and it seems only bit_length is currently implemented.

So if you are interested in implementing any of the other ones, that would be awesome. Let me know if you have any questions or need help getting started. I am happy to meet to give you an overview.

Hello, I am trying to implement the to_bytes method for integers. As mentioned here https://docs.python.org/3/library/stdtypes.html the method returns an array of bytes, which is a type, i.e. print(type((5).to_bytes(1,'big'))) --> <class 'bytes'>

My question is that do we want to implement:

A new type, i.e. implement the class 'bytes'
Just print the string corresponding to the byte array, i.e. print((1023).to_bytes(2,'big)) --> b'\x03\xff'
Instead of a byte array make a list that corresponds to the byte array, i.e. print((1023).to_bytes(2,'big)) --> [3,255]
Something else

Also I will appreciate it if you would like to add any other tips that can help me out! Thanks!

@zeproffesor

Thanks @zeproffesor, great question. I opened up a dedicated issue (#1187) to discuss the bytes type.

Until then just return a string. Once we decided how to handle the bytes type, we can upgrade it.

Okay! Thanks for the clarification, I'll begin working on the string implementation then.

Thanks! Feel free to open a Draft PR and post what you have and we can help if you get stuck.

@certik

@certik Created a draft pull request. Please review! Thanks!

bit_length() is a built-in method in Python that returns the number of bits required to represent an integer in binary, excluding the sign and leading zeros.

For example, the binary representation of 9 is 0b1001, which has a length of 4 (excluding the leading 0's). Therefore, num.bit_length() returns 4.

Here's an example:

num = 9
bit_length = num.bit_length()
print(bit_length) # output: 4
You can use bit_length() method on any integer in Python.

Hi! Is anyone still working on this? I am quite new to compilers but I plan on helping you guys :)
Project looks promising!

I am working on a PR for this issue

@OmarMesqq

@OmarMesqq perfect! Go ahead and work on it. A lot of these are implemented, but I think some are still missing. If you need any help, please ask!

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Implement a set of built-in methods to be used on strings/integers/.... #281

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