try and except in Mojo

Catching an error keeps the program running.

def parse_count(text: String) raises -> Int:
    if text == "":
        raise Error("empty input")
    return Int(text)

def main():
    try:
        print(parse_count("17"))
        print(parse_count(""))
    except e:
        print("recovered:", String(e))

How it works

1. The try block holds the calls that might raise.
2. except e: binds the error so it can be inspected.
3. String(e) renders the message for printing.

Keywords and builtins used here

• Error
• Int
• String
• def
• except
• if
• main
• parse_count
• print
• raise
• return
• try

The run, in numbers

Lines

11

Characters to type

210

Tokens

63

Three-star pace

85 tpm

At the three-star pace of 85 tokens a minute, this run takes about 44 seconds.

Type this snippet

Step 2 of 3 in Errors, step 24 of 26 in Language basics.

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