const MaxBits
MaxBits bounds a BitSet so allocation and iteration stay predictable.
v0 source pure
Package bitset is a dense, fixed-capacity bit vector as a pure, reusable package: a compact set of small non-negative...
View source
gno.land/p/moul/x/daily/bitset/v0
Dense fixed-capacity bit vector — New, FromSlice, Set, Clear, Flip,
Has, Count, Slice, Clone, Union, Intersect, Difference,
SymmetricDifference, Equal, MaxBits.
A compact set of small non-negative integers. Storage is []uint64 of
ceil(n/64) words, so 1024 bits cost 16 words instead of 1024 booleans — the
reason to reach for this on chain, where every byte is paid for.
1import "gno.land/p/moul/x/daily/bitset/v0"
2
3b := bitset.FromSlice(20, []int{1, 2, 3})
4c := bitset.FromSlice(20, []int{3, 4})
5bitset.Union(b, c).Slice() // [1 2 3 4]
6bitset.Intersect(b, c).Slice() // [3]
7b.Count() // 3
Capacity is fixed at construction: operations are bounds-checked and return
false out of range rather than growing, because silent growth would make gas
unpredictable. Has on an out-of-range index is simply false — something that
cannot be a member is not a member.
Combining two sets of different capacities returns nil rather than padding
one silently; a size mismatch is a caller error worth surfacing.
MaxBits (65536) caps allocation. Note String() prints bit 0 first, so it
reads in index order — the reverse of binary notation.
Live demo: r/moul/x/daily/bitsetdemo
· render it at /r/moul/x/daily/bitsetdemo/v0.
Part of moul/gno-contracts — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.
🧪 Highly experimental — potentially vibe-coded. Not audited; may break, change, or be removed at any time. Do not use with anything of value. Full disclaimer: DISCLAIMER.
Package bitset is a dense, fixed-capacity bit vector as a pure, reusable package: a compact set of small non-negative integers with the usual set algebra (union, intersection, difference).
Storage is a []uint64 of ceil(n/64) words, so 1024 bits cost 16 words rather than 1024 booleans — the reason to reach for this on chain, where every byte is paid for.
Capacity is fixed at construction and every operation is bounds-checked rather than growing: an out-of-range index is a caller bug, and silently growing would make gas unpredictable.
A live demo of this package is at r/moul/x/daily/bitsetdemo(/r/moul/x/daily/bitsetdemo/v0).
1
7
func Equal
Equal reports whether two sets have the same capacity and the same bits.
func Difference
Difference returns a \ b, or nil when the capacities differ.
func FromSlice
FromSlice builds a BitSet of capacity n containing the given indices. Out-of-range indices are ignored.
func Intersect
Intersect returns a ∩ b, or nil when the capacities differ.
func New
New returns a BitSet holding bits [0, n). n is clamped to [0, MaxBits].
func SymmetricDifference
SymmetricDifference returns a △ b, or nil when the capacities differ.
func Union
Union returns a ∪ b, or nil when the capacities differ. Mismatched capacities are a caller error rather than something to silently pad.
1
type BitSet
structBitSet is a fixed-capacity set of integers in [0, n).
Methods on BitSet
func Cap
method on BitSetCap returns the capacity in bits.
func Clear
method on BitSetClear turns bit i off and reports whether i was in range.
func Clone
method on BitSetClone returns an independent copy.
func Count
method on BitSetCount returns the number of set bits (popcount).
func Flip
method on BitSetFlip inverts bit i and reports whether i was in range.
func Has
method on BitSetHas reports whether bit i is set. Out of range is false, never a panic: membership of something that cannot be a member is simply false.
func InRange
method on BitSetInRange reports whether i is a valid index.
func Set
method on BitSetSet turns bit i on and reports whether i was in range.
func Slice
method on BitSetSlice returns the set bits in ascending order.
func String
method on BitSetString renders the set as '0'/'1' from bit 0 upward, which reads left-to-right in index order (note this is the reverse of binary notation).
1
- strings stdlib
