-- Labelled args (ILO-71)
-- Optional `name:value` syntax at call sites for arity-4+ functions.
-- Labels resolve to positional by parameter name, so order doesn't matter.
-- Works for builtins, user functions, and paren-form calls.
-- User-defined arity-4 function
combine a:t b:t c:t d:t>t;fmt "{} {} {} {}" a b c d
-- Demonstrates:
-- 1. All-labelled call (order matches declaration)
-- 2. All-labelled call (reversed order — same result)
-- 3. Mixed positional + labelled
-- 4. Builtin with labelled args (dtfmt)
-- 5. Paren-form labelled call
-- 6. Unknown label → clear ILO-P019 diagnostic
main>t;
-- 1. All-labelled, declaration order
r1=combine a:"alpha" b:"beta" c:"gamma" d:"delta";
-- 2. All-labelled, reversed — identical result
r2=combine d:"delta" c:"gamma" b:"beta" a:"alpha";
-- 3. Mixed: first two positional, last two labelled
r3=combine "alpha" "beta" d:"delta" c:"gamma";
-- 4. Builtin dtfmt with labelled args (epoch + fmt reversed)
epoch=1700000000;
r4tmp=dtfmt fmt:"%Y-%m-%d" epoch:epoch;
r4=?r4tmp{~v:v;^e:"err"};
-- 5. Paren-form labelled call
r5=combine(d:"delta", c:"gamma", b:"beta", a:"alpha");
-- 6. Positional (unchanged behaviour)
r6=combine "alpha" "beta" "gamma" "delta";
fmt "{}\n{}\n{}\n{}\n{}\n{}" r1 r2 r3 r4 r5 r6