Collections and strings

Lists, arrays, dicts, and strings are compiler-known types with runtime helpers in sere_rt. len is an intrinsic that also dispatches to __len__.

Lists

xs: list[i32] = [1, 2, 3]
xs.append(4)
xs[0] = 10
print(len(xs), xs[1], xs[1:], xs[:2], xs[1:3], xs[:])

xs.append(v) and append(xs, v) both add to a list. del xs[i] removes an index.

Comprehensions:

comp: list[i32] = [x for x in range(0, ..., 3)]

Arrays

arr: array[i32] = array[i32](1, 2, 3)

Fixed, constructed by the array intrinsic. Not a growable list.

Dicts

ages: dict[str, i32] = {"ada": 36}
ages["ada"] = 37
empty: dict[str, i32] = dict[str, i32]()
del ages["ada"]

Empty dicts need the typed constructor. del table[key] removes a key.

Strings

hello: str = "Hello"
assert hello[0] == "H"
assert hello[-1] == "o"
assert hello[1:4] == "ell"
assert "ell" in hello
assert hello + "!" == "Hello!"
assert hello * 2 == "HelloHello"

Indexing and slicing produce str (a one-character string for a single index). for ch in hello walks those one-character strings.

F-strings and triple quotes are lexical forms; they still type as str. Regex literals are not strings — they type as regex. See Lexical structure.

len

Works on list, array, dict, str, and any type with __len__. The intrinsic is the primitive; a dunder is the extension point.