"quick" / "easy" fixes

for global initialization cycles, report also starting and ending lines

milestones

interop type foundation (implemented)

unsigned integers, floats, and target-dependent c scalar types
atomic c_* primitive types remain distinct until target-aware lowering
c_func and pointer-only c_struct; c remains an ordinary identifier
keep binding mutability (:: / =) separate from element or pointee mutability (mut)
arrays and indexing
- [N]T: array with N logical elements
- [N;S]T: array with N logical elements followed by sentinel S
pointers
- @T / @mut T: non-null single-item pointer without arithmetic
- *T / *mut T: non-null many-item pointer with arithmetic
- optional pointers represent nullable pointers (i.e. ?@T / ?@mut T, ?*T / ?*mut T)
slices and slicing
- []T: pointer and length
- [;S]T: pointer and length with a sentinel invariant
- ordinary slices do not guarantee null termination
string literals as immutable sentinel slices backed by static arrays (superseded by milestone 3.5)
character literals
optionals with trapping unwrap and fallback operations
native structs with compiler-controlled layout
pointer-only c_struct support with target c layout
- Some :: c_struct { ... }: defined c-layout struct
- Some :: c_struct: opaque c-layout struct
- passing c structs by value was deferred until milestone 4.1

restricted c header imports (implemented)

treat an imported header as a synthetic, file-local package namespace
- native :: import "relative/path/to/header.h"
import functions, typedefs, scalar types, and pointers to opaque records
keep implementation linking separate from header imports
cache imports by canonical header path and target/include/define configuration
diagnose unsupported declarations when referenced
dynamically load libclang behind a replaceable c importer boundary

c variadic calls (implemented)

represent c variadics as a fixed parameter count plus a variadic flag
apply c default argument promotions at call sites
emit LLVM c-variadic declarations and calls
keep native brolang variadics and tuple design separate

3.5. sentinel pointers and c strings (implemented)

add sentinel many-item pointers: [*;S]T
represent string literals as immutable pointers to statically stored sentinel arrays: @[N;0]u8
arrays expose .len but no .ptr; slices and pointers-to-arrays expose sentinel-preserving .ptr
allow pointer-to-array .len, indexing, slicing, pointer decay, and slice construction without explicit dereference
preserve or forget sentinel information through compatible pointer and slice coercions without copying arrays
allow zero-terminated immutable byte pointer views to convert to immutable *c_char and [*;0]c_char
keep u8 and c_char distinct to preserve target-dependent scalar c semantics
reject general u8/c_char interchange, slice-to-pointer coercion, and conversion to mutable c character pointers

advanced c interop

by-value records and unions (implemented)
- complete plain imported structs/unions and manual c_struct values
- fixed C arrays inside imported records
- keyed struct literals and exactly-one-field union literals
- field reads/writes, storage, and fixed-signature calls/returns
- aarch64-macos small aggregate, homogeneous float aggregate, and indirect ABI lowering
- keep incomplete, bitfield, packed, flexible-array, qualified-field, and otherwise non-plain records pointer-only
- keep C variadic record arguments unsupported
function pointers and callbacks (implemented)
- imported C function pointer typedefs lower to nullable pointer types
- manual ?*c_func(...) T callback type spelling
- concrete c_func declarations/definitions can be passed as callback values
- postfix calls through non-null function pointers, including callback?(...)
- fixed and C-variadic callback ABI emission through LLVM indirect calls
external variables (implemented)
- imported external C object variables lower to direct LLVM external global references
- top-level const object variables are read-only from brolang
- mutable external scalars/records can be assigned through qualified package globals
- unsupported variable types remain lazy diagnostics when referenced
object-like macro constants (implemented)
- scalar integer/float literal macros import as immutable globals
- CLITERAL(Type){ ... } / (Type){ ... } record literal macros import as immutable globals
- function-like macros and non-literal macro expressions remain unsupported
static inline functions (implemented)

control flow (implemented)

boolean expressions (implemented)
- bool type with true / false literals
- comparison operators: ==, !=, <, <=, >, >= (numeric operands widen; bool supports only == / !=)
- operators: and, or, !
- lazy evaluation / short-circuit evaluation
if statements (implemented). example: if condition { ... } else if { ... } else { ... }
- conditions must be bool; block-scoped locals with shadowing across blocks
- lowered through new Label / Br / Cond_Br IR opcodes (alloca-backed locals, no phi nodes)
conditional unwrapping for optionals (?T) (implemented): if val |v| { ... } else { ... } - unwrap val into v if it is not none
- single immutable binding scoped to the then-block; v not visible in else or after the if
- | lexes as a new Pipe token; the .If reuses AST name / HIR local to carry the binding (no new statement kind)
- new Optional_Is_Some / Optional_Value IR opcodes (the Unwrap presence-test + extract, minus the trap)
conditional unwrapping with guard clause (implemented): if val |v : v >= 10| { ... } else { ... } - enter the then-block when val is not none and the guard is true
multi-unwrap (implemented; see section below)
while loops (implemented; operates on boolean conditions). examples:
- while condition { ... } - iterate while the condition is true
- while condition : i = i + 1 { ... } - execute the update after each completed iteration
- the condition and update may be parenthesized independently for visual clarity
- update targets must already be declared and mutable; loops do not introduce implicit induction variables
- compound assignment (+=) remains deferred
ranges (implemented; see section below)
for loops (implemented; operates on ranges, arrays, slices, and pointers-to-arrays). examples:
- for items |item| { ... } - capture just the item value in the array/slice (uses copy semantics, i.e. gets a T)
- for (&items) |@item| { ... } - capture a pointer to each array element; its @T / @mut T mutability follows the iterable
- for items_slice |@item| { ... } - slices already refer to backing storage and support pointer capture directly
- for items |item, idx| { ... } - capture item and its index index in the array/slice
- for 0..10 |i| { ... } - iterate over the range 0..10 (exclusive)
- for 0..=10 |i| { ... } - iterate over the range 0..10 (inclusive)
- for 0..(len) |i| { ... } or equivalently for 0..=(len - 1) |i| { ... } - calculating range bounds, expressions must be parenthesized
for all conditionals/guards, parentheses are optional but allowed for visual clarity

compound assignment: +=, -=, *=, /=
enums (native and c interop) (see below)
distinct types (see below)

A word on multi-unwrap

Unwrap multiple optionals with and. This short-circuits: if the first optional is none, subsequent expressions are not evaluated.

name: ?[]u8 = get_name()
age: ?u8 = get_age()
if name and age |n, a| {
    # both n and a are guaranteed non-none here
    print("{s} is {d} years old", {n, a})
}

With guard clause on multiple values:

if name and hat |n, h : n == "Huginn" and h.brand == .gucci| {
    print("{s}'s got that drip\n", {n})
}

Parentheses around the expression are optional, but can aid readability when combined with guards:

# without parentheses
if name and hat |n, h : guard| { ... }

# with parentheses for clarity
if (name and hat) |n, h : guard| { ... }

A word on lazy / short-circuit evaluation

The and in multi-unwrap short-circuits left-to-right:

if get_name() and get_hat() |n, h| {
    # get_hat() is only called if get_name() returned non-none
}

This is important for avoiding unnecessary computation or side effects.

A word on ranges

Ranges represent a sequence of values, commonly used in for loops, and is itself a value type:

0..10      # exclusive: 0, 1, 2, ..., 9
0..=10     # inclusive: 0, 1, 2, ..., 10

Parenthesization rule: Each side of .. must be either a simple term (literal or identifier) or a parenthesized expression. This eliminates precedence ambiguity:

0..10           # OK: both sides are literals
0..n            # OK: both sides are simple
0..(n + 1)      # OK: complex expression is parenthesized
(a + 1)..(b - 1)  # OK: both sides parenthesized
# 0..n + 1      # ERROR: must parenthesize complex expressions

This rule keeps the grammar simple and forces clarity at the call site — no precedence rules to remember. Also, being a value type, ranges can be assigned to variables and passed around like any other value. Range bounds are evaluated once, must have compatible concrete integer types, and descending ranges are empty.

For-loop captures are immutable and scoped to the loop body. Sequence index captures are usize. Pointer capture uses |@item|; arrays must be passed by pointer (for example &items), while slices can be used directly. Sentinel elements are not included in iteration.

A word on distinct types

Distinct types are considered distinct from their backing type. They do not implicitly coerce to their backing type.

# distinct type
UserID :: distinct u32

# instantiate distinct type
my_id UserId :: UserID(42) # value must be of to backing type

A word on enums

# standard enums
Animal :: enum {
    dog
    cat
    bird
    lizard
}

# enums with backing type
Nat :: enum(u8) { # in this case, a maximum of 256 values are possible
    one # default: implicitly starts from value 0
    two
    three
    four
    five
}

# enums with backing type with explicit associated values
# note: must not be jumbled (i.e. `first_val = 1` must come before `other_val = 2`), but is allowed to be discontiguous (i.e. `one = 1` can be followed by `three = 3` without `two = 2` in between)
Nat :: enum(u8) {
    one = 1
    two = 2
    three = 3
    # no four
    five = 5
}

# enums with backing type with semi-implicit associated values
Nat :: enum(u8) {
    one = 1 # starts from value 1
    two     # implicitly gets value 2
    three   # etc...
    four
    five
}

# using enums
dog_tag1 Animal :: Animal.dog
dog_tag2 Animal :: .dog # type inferred

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