Lexicon & syntax

cobra4 is brace-based with English keywords. The grammar is LALR(1) and lives in cobra4/grammar.lark.

Identifiers

NAME: [A-Za-z_][A-Za-z0-9_]*

Reserved keywords

if elif else while for each in not and or is True False None
fn class return raise break continue pass
match case try catch finally
use as where every on event from to parallel
serve deploy lang

Comments

# only `#` opens a comment.
# `//` is always integer division — never a comment.

Numbers

42         # int
3.14       # float
1.5e-3     # scientific

Hex / oct / binary literals (0x1F, 0b101) and underscore separators (1_000_000) are not supported. Use int("0x1F", 16) if needed.

Strings

All non-raw strings are interpolated:

"hello {name}"               # interpolation, no `f` prefix needed
"escape {{braces}}"          # `{{` and `}}` are literal braces
r"C:\Users\path"             # raw — no escapes
"""
multi
line
"""

There is no explicit format spec like "{x:.2f}". Use format(x, ".2f") or "{round(x, 2)}".

Operators

Category	Operators
Arithmetic	+, -, *, /, //, %, **
Bitwise	&, \|, ^, ~, <<, >>
Comparison	==, !=, <, >, <=, >=, is, is not, in, not in
Bool	and, or, not
Special	?. (safe-nav), ?? (null-default)
Assign	=, +=, -=, *=, /=, //=, %=, **=, &=, \|=, ^=, <<=, >>=

There is no walrus (:=), no pipe (|>), and no matrix multiply (@ is decorator-only).

Safe-nav and default

name = req?.params?.name ?? "anon"

?. returns None if the target is None, and uses .get() when the target is a dict instead of getattr — so req?.params?.name works whether params is an object or a dict.