Parametric functions in Mojo

Square brackets take compile-time parameters; parentheses take runtime arguments.

def scaled[factor: Int](value: Int) -> Int:
    return value * factor


def repeated[times: Int](text: String) -> String:
    var out = String()
    for _ in range(times):
        out += text
    return out


def main():
    print(scaled[3](7), scaled[10](7))
    print(repeated[3]("ha"))

How it works

1. scaled[factor: Int] bakes the multiplier into each specialization.
2. scaled[3](7) and scaled[10](7) compile to two separate functions.
3. repeated[times] shows a parameter driving a loop bound.

Keywords and builtins used here

• Int
• String
• def
• for
• main
• print
• range
• repeated
• return
• scaled
• var

The run, in numbers

Lines

14

Characters to type

256

Tokens

79

Three-star pace

70 tpm

At the three-star pace of 70 tokens a minute, this run takes about 68 seconds.

Type this snippet

Step 2 of 5 in Compile-time Mojo, step 2 of 22 in Parameters & SIMD.

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