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.
The script is in tools/ rather than thrown away, because two lanes are
writing Flan in the old spelling right now and their files need the same
pass at merge.
It works on forms, not on text: a keyword becomes a dot only where it sits
in a field-label position inside a brace, so an enum member in value
position, a map key inside an EDN string and a type-position {K V} are all
left alone. :keys keeps its colon -- it names no field.
An index expression inside a place, a place under addr, and a
restart-case clause body are each the only route to a function in
reach-walk.flan. Drop any one of the three from the walk and the
function is not emitted, so the program stops linking rather than
answering wrong; each mutation was planted and watched fail here. The
addr case goes through a deref place on purpose, so the index case
cannot stand in for it.
