Expressions

Arithmetic

def main() -> None:
    print(1 + 2 * 3)    # 7
    print((1 + 2) * 3)  # 9
    print(10 - 3 - 2)   # 5
    print(-3 + 5)       # 2

Comparisons

a == b
a != b
a < b
a <= b
a > b
a >= b

Chained comparisons are supported and each operand is evaluated once:

def main() -> None:
    print(1 < 2 < 3)    # True
    print(5 < 4 < 3)    # False
    print(1 < 2 + 3)    # True

Boolean operators

def main() -> None:
    print(True and False)
    print(True or False)
    print(not False)
    print(not 1 > 2)
    print(True or False and False)

String operations

def main() -> None:
    word = "compiler"
    print(word[0])           # char
    print(word[3])           # char
    print(word[:4])          # slice → str
    print(word[4:])
    print(word[0:4])
    print(word[:])
    print("a" + "b" + "c")  # concatenation
    print(len("hello"))      # length → int

    # Postfix on literals and expressions
    print("hello"[1])
    print("hello"[1:4])
    print(("ab" + "cd")[1])

String methods:

def main() -> None:
    value = "compiler"
    print(value.starts_with("com"))
    print(value.ends_with("ler"))
    print(value.find("pil"))
    print(value.split("pi"))
    print(value.replace("pile", "pact"))

char / int conversion

import chars

def main() -> None:
    ch = "hello"[1]
    print(ch)
    print(ord(ch))
    print(chr(65))
    print(chars.is_digit('7'))
    print(chars.is_alpha('Q'))
    print(chars.is_space(' '))

List and dict operations

See Types for the full list of available methods.

def main() -> None:
    xs: list[int] = [1, 2, 3]
    xs.append(4)
    xs.pop()
    xs.clear()
    print(len(xs))

    colors: dict[str, str] = {"apple": "red"}
    colors["sky"] = "blue"
    colors.set("grass", "green")
    print(colors.contains("apple"))
    print("apple" in colors)
    print(colors.get_or("missing", "none"))
    print(colors.keys())
    print(colors.values())
    print(colors.items())

Tuple indexing

Tuple indexing requires a non-negative integer literal:

def main() -> None:
    pair: (int, str) = (1, "hello")
    print(pair[0])
    print(pair[1])

Enum variant access

enum Color:
    RED
    GREEN

def main() -> None:
    print(Color.RED)

Enum variant lookup is compile-time and module-aware.

Typed JSON calls

json.from_string[Type](text) and json.to_string(value) are compiler built-ins:

import json

class User:
    name: str
    age: int

def main() -> None:
    user = json.from_string[User]("{\"name\":\"ann\",\"age\":3}")
    print(user)
    print(json.to_string(user))