Import Python standard library with Mojo

Question

I just started to play around with Mojo. I am having a hard time importing modules from the Python standard library even though, according to the examples reported in the quick start guide, importing Python's module should be a breeze. What am I missing?

For example, to import the "time" module, I have tried: let time = Python.import_module("time")

However, I get a couple of errors I don't get.

cannot call function that may raise in a context that cannot raise
use of unknown declaration 'time', 'fn' declarations require explicit variable declarations

I have resolved the first error by adding raises to the function declaration and adding a try/except block to the import line. Although, I am not satisfied with this, it feels too verbose. Is there a better way?

I still don't have a solution for the second error. Can anyone suggest a solution?

fn main() raises:
    #added raises and following try/except block
    #to fix "Error 1"
    
    from python import Python
    try:
        let time = Python.import_module("time")
    except:
        print('Import Error')
        
    let s = time.time() #raises "Error 2"
    print('Hello World')
    let e = time.time()
    print("Done in", e-s, "seconds")

Jesse Sealand · Accepted Answer · 2023-09-25 13:39:35Z

1

Here is a working solution. I moved the import python statement outside of the function. I think importing it inside of your main() raises a context error 'somehow' but we're all still learning more about mojo as it develops. Since python was not loaded, the time package was also not loaded which explains why you got error #2.

from python import Python

fn main() raises:
    
    let time = Python.import_module("time")

    let s = time.time()
    print('Hello World')
    let e = time.time()
    
    print("Start (s):", s)
    print("End (s): :", e)
    print("Done in", (e-s), "seconds")

# Hello World
# Start (s): 1695648805.9679005
# End (s): : 1695648805.967926
# Done in 2.5510787963867188e-05 seconds

answered Sep 25, 2023 at 13:39

Jesse Sealand

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4 Comments

alec_djinn Over a year ago

Are you running this in a notebook cell or from the terminal?

Jesse Sealand Over a year ago

I ran this from a notebook cell.

alec_djinn Over a year ago

Can you try to run it as stand-alone executable instead? I get this error outside the notebook

alec_djinn Over a year ago

Your code is correct. It works. Something was probably off with my installation, as the errors disappeared once Mojo was reinstalled.

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