samufi Posts - Answer Overflow

samufi

•Created by samufi on 9/23/2024 in #questions

What does the keyword `capturing` do?

I noticed that the keyword capturing is necessary when I want to time code via time_function. For example,

from time import time_function

fn closure() capturing:
    my_function()

print(time_function[closure]() * 1e-9)

from time import time_function

fn closure() capturing:
    my_function()

print(time_function[closure]() * 1e-9)

What is going on under the hood if I am using the keyword capturing? I have not found documentation on this.

2 replies

MModular

•Created by samufi on 9/21/2024 in #questions

How can I use a fixed-size integer type to index a list?

I want to use a fixed-size integer value as index of a list. However, I get the "no matching method in call to 'getitem'" error.

var l: List[Int] = List[Int]()
l.append(1)
var ind: UInt32 = 0
print(l[ind])

var l: List[Int] = List[Int]()
l.append(1)
var ind: UInt32 = 0
print(l[ind])

How can I use a 32 bit unsigned integaer such as ind in the example above as index for a list (preferably without performance penalty and lengthy additional syntax)?

7 replies

MModular

•Created by samufi on 8/5/2024 in #questions

Is there a (N-D) contiguous data structure for non-trivial structs?

I need a data strucuture that is a 2-dimensional array of (inline) lists of pairs. That is, if subdata = data[i][j], then subdata is a dynamic data structure that contains tuples of size 2. My take on solving this was to use a Tensor for the 2-D data structure, an InlinedFixedVector for the flexible part, and a StaticTuple for the pair.

from tensor import Tensor
from collections import InlinedFixedVector
from utils import StaticTuple


struct MyStruct:
    var data: Tensor[InlinedFixedVector[StaticTuple[Float64, 2], 10]]

from tensor import Tensor
from collections import InlinedFixedVector
from utils import StaticTuple


struct MyStruct:
    var data: Tensor[InlinedFixedVector[StaticTuple[Float64, 2], 10]]

However, I get the following error:

'Tensor' parameter #0 has 'DType' type, but value has type 'AnyStruct[InlinedFixedVector[StaticTuple[SIMD[float64, 1], 2], 10]]'

'Tensor' parameter #0 has 'DType' type, but value has type 'AnyStruct[InlinedFixedVector[StaticTuple[SIMD[float64, 1], 2], 10]]'

I figure that Tensors can only hold trivial data types. If so, is there a good general data structure for multi-dimensional data? I was thinking of putting InlineList into a self-made 2D represntation of List, but InlineList does not implement CollectionElement (as of yet?).

6 replies

MModular

•Created by samufi on 8/2/2024 in #questions

How can I write asynchronous code?

How can I implement asynchroneous code in mojo (using async etc.)? In the Changelog, I find the following example (slightly adjusted):

async fn add_three(a: Int, b: Int, c: Int) -> Int:
    return a + b + c

async fn call_it():
    var task = add_three(1, 2, 3)
    print(await task)

async fn add_three(a: Int, b: Int, c: Int) -> Int:
    return a + b + c

async fn call_it():
    var task = add_three(1, 2, 3)
    print(await task)

This gives me the following compiler error:

test_async.mojo:39:17: error: 'Coroutine[Int, {}]' is not copyable because it has no '__copyinit__'
    print(await task)
                ^~~~

test_async.mojo:39:17: error: 'Coroutine[Int, {}]' is not copyable because it has no '__copyinit__'
    print(await task)
                ^~~~

I do not understand this error, as I thought that Coroutine is register passable (as visible in the source code). What works is

async fn add_three(a: Int, b: Int, c: Int) -> Int:
    return a + b + c

async fn call_it():
    var task = await add_three(1, 2, 3)
    print(task)

async fn add_three(a: Int, b: Int, c: Int) -> Int:
    return a + b + c

async fn call_it():
    var task = await add_three(1, 2, 3)
    print(task)

However, if I always put await on the right hand side, I will never be able to execute code asynchroneously, as I am always waiting until the line has finished. What am I doing wrong / where is my misconception? (Or is this simply a bug?) In the changelog it furthermore says that tasks can be "resumed" after completion (see here). What is meant by "resume" and how do I do that? I am working with the nightly built mojo 2024.7.2005 (96a1562c). Addon: I asked this question on the Q&A page and on SO some time ago. Sorry for the double posting; I just do not know what is the best way to get in touch with people who can help. I will keep the copies up to date (or delete them if people think this would be better).

11 replies

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