Conditional expressions in Mojo

a if cond else b picks a value without opening a block.

def parity(n: Int) -> String:
    return "even" if n % 2 == 0 else "odd"

def main():
    for n in range(1, 6):
        var size = "big" if n > 3 else "small"
        print(n, parity(n), size)

How it works

1. parity returns the whole branch as a single expression.
2. The same form works inline when assigning size.
3. Both arms have to produce the same type.

Keywords and builtins used here

• Int
• String
• def
• else
• for
• if
• main
• parity
• print
• range
• return
• var

The run, in numbers

Lines

7

Characters to type

168

Tokens

61

Three-star pace

90 tpm

At the three-star pace of 90 tokens a minute, this run takes about 41 seconds.

Type this snippet

Step 5 of 5 in Flow control, step 11 of 26 in Language basics.

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Conditional expressions in other languages

• Python