(t x) is not a name is_cast knows - t is not a machine type - so it is
its own arm, admitted by numeric? because a cast produces a number.
vec-new, pool-new and map-new all reach the one list of what names a
type, so the spike's line for vec-new had already covered the other two;
zeroed takes its type from the position it is written in. All four are
pinned in programs/generics.flan.
swap!, reverse!, sort!, sort-by!, index-of, min-of, max-of, map!,
reduce and filter, each written once over $t. Every call site in the
corpus moves with them.
min-of and max-of are not min and max because min and max are builtins
over two or more numbers and nothing shadows a builtin. These reduce a
slice, which is a different operation at a different arity.
sort-bytes! did not collapse into sort!, and the reason is the point of
the predicates: a [u8] is not ordered? and cannot be, because < is an
instruction and comparing two slices lexicographically is a loop. It is
sort-by! with bytes<? written in, one line, keeping its name and its
stability note. sum-i32/sum-f32 and append-i64!/append-f64! stay for the
reasons the spike gave.
Not what the notes predicted: none of the ten collapses on a signature
change alone. filter and reduce need copyable? because the checker
demands it - reduce's accumulator at (Vec i32) is a double move - and
the rest declare it because a slice of owning elements would have them
duplicating headers.
