jolt/.dirge/memory/PITFALLS.md
Yogthos 33a5b7e7a4 feat: persistent vector (working) + HAMT hash map (wip)
PersistentVector: 17-form .clj source, fully working.
- 32-way branching trie with tail optimization
- pv-conj, pv-nth, pv-assoc, pv-pop, vector?, vector constructor
- instance? check works on deftype tables
- .-field accessor syntax for deftype fields

api.janet: :mutable? compile flag for opt-out
- Default: persistent data structures loaded
- Pass {:mutable? true} to use Janet native types

Supporting changes (evaluator/core):
- 17 new primitives: bit ops, array ops, unchecked math, hash, cond
- loop macro, zero?, dec/inc, defn multi-arity
- instance? for deftype tables (get val :jolt/deftype)
- defrecord builds maps at expansion time
- .-field field access in default function application path

PersistentHashMap: 24-form HAMT source loads OK.
- BitmapIndexedNode/PersistentHashMap deftypes
- mask, bitpos, bit-count, index helpers
- phm-assoc/phm-get/phm-without/phm-contains? stubs
- bmn-assoc insert path structured, bitmap propagation wip
2026-06-02 11:51:39 -04:00

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Janet `try` syntax: the error handler clause `([err] handler)` must be on ONE line. Splitting `([err]\n handler)` causes "unexpected closing delimiter )" parse error at runtime. This is a Janet parser limitation, not a Jolt issue. Fix: always write `(try body ([err] handler-body))` on one line, or use `(do ...)` for multi-line handlers: `(try body ([err] (do ...)))`.
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Janet `(try body ([err] handler))` form: the handler clause takes exactly ONE parenthesized expression. `(try (do ... :ok) ([err] (printf \"%q\" err) :fail))` is valid — the handler returns :fail. But `(try (do ... :ok) ([err] (printf \"%q\" err) :fail)))` with extra closing parens causes \"unexpected closing delimiter\" errors. When generating Janet source from Python, verify paren balance with a counter. Also: `(def result (try ... ([err] (string err))))` is valid — string function call is the single handler expression. Getting this wrong wastes many iterations.
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`binding-get` uses `return` from inside while loop within fn body — this signals an error in Janet (user0 tuple). Must use `(var result :jolt/not-found)` + `(when (in t name) (set result ...) (set t nil) (break))` pattern. Cannot use `return` for early exit from loops in Janet.