jolt/test/spec/multimethods-spec.janet
Yogthos a06c39266a core: delete seed fns shadowed by the overlay; fix methods/remove-all-methods
The seed copies of inst?/inst-ms and the multimethod table ops
(get-method/methods/remove-method/remove-all-methods/prefer-method) are dead
code — the overlay redefines all of them (20-coll.clj, 30-macros.clj) — so
they're deleted along with duplicate bindings-table entries (unreduced,
eduction, unchecked-inc/dec/add/subtract).

New spec rows for methods/remove-all-methods caught two real bugs in the
evaluator's setup fns: methods-setup returned the live host table (count
rejected it, and callers could mutate dispatch state), and
remove-all-methods-setup swapped in a fresh table the dispatch closure never
saw. methods now returns a phm snapshot; remove-all-methods clears in place.
2026-06-11 09:21:25 -04:00

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# Specification: multimethods & hierarchies.
(use ../support/harness)
(defspec "multimethods / dispatch"
["dispatch on value" "\"two\""
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") (defmethod f 2 [_] \"two\") (f 2))"]
["dispatch on keyword fn" "\"circle\""
"(do (defmulti area :shape) (defmethod area :circle [_] \"circle\") (area {:shape :circle}))"]
[":default method" "\"other\""
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") (defmethod f :default [_] \"other\") (f 99))"]
["no match throws" :throws
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") (f 99))"]
["multiple args" "5"
"(do (defmulti g (fn [a b] a)) (defmethod g :add [_ b] b) (g :add 5))"]
["get-method" "\"one\""
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") ((get-method f 1) 1))"]
["remove-method" :throws
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") (remove-method f 1) (f 1))"]
["methods" "\"one\""
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") ((get (methods f) 1) 1))"]
["methods count" "2"
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") (defmethod f 2 [_] \"two\") (count (methods f)))"]
["remove-all-methods" :throws
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") (defmethod f 2 [_] \"two\") (remove-all-methods f) (f 1))"]
["remove-all-methods empties the table" "0"
"(do (defmulti f identity) (defmethod f 1 [_] \"one\") (remove-all-methods f) (count (methods f)))"])
(defspec "multimethods / hierarchies"
["derive + isa?" "true" "(do (derive ::child ::parent) (isa? ::child ::parent))"]
["isa? reflexive" "true" "(isa? ::x ::x)"]
["isa? unrelated" "false" "(do (derive ::a ::b) (isa? ::a ::c))"]
["parents" "true" "(do (derive ::c ::p) (contains? (parents ::c) ::p))"]
["ancestors" "true" "(do (derive ::c ::p) (derive ::p ::g) (contains? (ancestors ::c) ::g))"]
["descendants" "true" "(do (derive ::c ::p) (contains? (descendants ::p) ::c))"]
["dispatch via hierarchy" "\"animal\""
"(do (derive ::dog ::animal) (defmulti speak identity) (defmethod speak ::animal [_] \"animal\") (speak ::dog))"]
["custom :default key" ":unknown"
"(do (defmulti classify :type :default :other) (defmethod classify :a [_] :alpha) (defmethod classify :other [_] :unknown) (classify {:type :zzz}))"]
["explicit :hierarchy" "\"a\""
"(do (def h (derive (make-hierarchy) ::dog ::animal)) (defmulti snd identity :hierarchy h) (defmethod snd ::animal [_] \"a\") (snd ::dog))"])
# prefer-method breaks isa-dispatch ties; ambiguity without a preference is
# an ERROR (jolt-heo — this used to silently take an arbitrary method).
(defspec "multimethods / prefer-method"
["preference picks the winner" ":rect"
"(do (derive :p/sq :p/rect) (derive :p/sq :p/shape) (defmulti pm1 identity) (defmethod pm1 :p/rect [x] :rect) (defmethod pm1 :p/shape [x] :shape) (prefer-method pm1 :p/rect :p/shape) (pm1 :p/sq))"]
["reverse preference" ":shape"
"(do (derive :q/sq :q/rect) (derive :q/sq :q/shape) (defmulti pm2 identity) (defmethod pm2 :q/rect [x] :rect) (defmethod pm2 :q/shape [x] :shape) (prefer-method pm2 :q/shape :q/rect) (pm2 :q/sq))"]
["ambiguity throws" :throws
"(do (derive :r/sq :r/rect) (derive :r/sq :r/shape) (defmulti pm3 identity) (defmethod pm3 :r/rect [x] :rect) (defmethod pm3 :r/shape [x] :shape) (pm3 :r/sq))"]
["isa dominance needs no preference" ":child"
"(do (derive :s/c :s/p) (defmulti pm4 identity) (defmethod pm4 :s/c [x] :child) (defmethod pm4 :s/p [x] :parent) (pm4 :s/c))"]
["prefers map shape" "true"
"(do (defmulti pm5 identity) (defmethod pm5 :a [x] 1) (defmethod pm5 :b [x] 2) (prefer-method pm5 :a :b) (contains? (get (prefers pm5) :a) :b))"]
["exact match needs no preference" ":exact"
"(do (derive :t/sq :t/rect) (defmulti pm6 identity) (defmethod pm6 :t/sq [x] :exact) (defmethod pm6 :t/rect [x] :parent) (pm6 :t/sq))"])