-- srt fn xs — sort by a key function. Phase 2 PR3c lifts the 2-arg form
-- off the tree-bridge: VM and Cranelift now run a native foreach + per-
-- element OP_CALL_DYN, then assemble the sorted list via OP_SRT_BY_KEY.
-- Closure callbacks dispatch natively (no tree re-entry per element).
-- Key: absolute value, so [-3,1,-2] sorts ascending by magnitude.
absv n:n>n;?<n 0 (-0 n) n
by-abs xs:L n>L n;srt absv xs
-- Key: string length, shortest first.
slen s:t>n;len s
by-len ws:L t>L t;srt slen ws
-- Capturing lambda: sort by distance from a caller-supplied centre.
-- `c` is captured into the closure; Cranelift OP_CALL_DYN handles it
-- without bouncing through the tree interpreter.
by-dist xs:L n c:n>L n;srt (x:n>n;d=-x c;?<d 0 (-0 d) d) xs
-- run: by-abs [-3,1,-2,4,-1]
-- out: [1, -1, -2, -3, 4]
-- run: by-len ["banana","fig","apple"]
-- out: [fig, apple, banana]
-- run: by-dist [1,5,3,9] 4
-- out: [5, 3, 1, 9]