09b4e3e1bd
- types.janet: ns? now accepts both structs and tables
(defensive for namespace-like tables created via @{...})
- core.janet: wire comment macro into core-bindings
(was in core-macro-names but missing from core-bindings)
- sci/lang_stubs.clj: minimal SCI type stubs for bootstrap
(IBox, HasName, IVar, DynVar protocols, SciUnbound/Var/Namespace deftypes)
- test-load-sci.janet: load stubs before SCI source files,
removed broken preprocessor
Before: 315 ok, 2 fail (SciVar + array/buffer)
After: 316 ok, 1 fail (only deftype in lang.cljc remains)
The remaining failure is lang.cljc's SciVar deftype with #?@ inserts
for JVM/CLJS-specific protocol implementations — a known limitation
for Phase 15 (SCI bootstrap).
3 KiB
| name | description |
|---|---|
| jolt-gotchas | Common pitfalls and workarounds discovered during Jolt implementation |
jolt-gotchas
Recurring pitfalls and their fixes discovered across all implementation phases.
PHM/Set Metadata Key Leakage
PHM and set internal keys (:jolt/deftype, :cnt, :buckets, :_meta, :jolt/type, :phm) leak into pairs/keys iteration. Must filter in merge, merge-with, keys, vals, and print-collection.
(when (and (not= k :jolt/deftype) (not= k :cnt)
(not= k :buckets) (not= k :_meta)
(not= k :jolt/type) (not= k :phm)) ...)
Keywords with # Are Invalid Janet Literals
:#inst, :#uuid cause parse errors. Use dynamic table construction:
(let [dr @{}] (put dr (keyword "#inst") fn) dr)
Janet break Only Works in Loops
Does NOT work inside let. Use (var found nil) + (set found val) (break) pattern.
Bare Tuples in eval Are Function Calls
(eval [1 2 3]) calls 1 as function. Use ['tuple 1 2 3] in data-structure emitter.
Janet case for Multi-Arity
Janet lacks Clojure-style multi-arity defn. Use (defn f [& args] (case (length args) 1 ... 2 ...)).
core-renames + core-fn-values Must Stay in Sync
Both tables must be updated together when adding core fns. Missing entries = silent nil returns. "-" is core-sub NOT core--.
set! Field Mutation Reader Quirk
(set! (.-x obj) val) parses as array with .-x symbol head — not as standalone .-x symbol. Check for this case before the (. obj -field) shorthand.
Janet cond Requires true Guard for Catch-All
A bare expression in the last position of cond is treated as a test clause (not body). Use true as the test:
(cond (nil? x) (buf "nil") (number? x) (buf (string x)) true (buf (string x)))
Without true, the last expression executes as a side-effect test between branches. Hit us in buffer-based write-value — raw tuple addresses leaked into REPL output.
REPL: Buffer-Based Output Prevents C-Runtime Interleaving
Janet's C runtime in jpm build executables interleaves native <tuple 0x...> output between prin statements. Solution: build entire output string in a buffer, then output atomically with a single print call. Use write-value/v buf + print-value creates buffer → print (string buf).
Janet struct? Returns true for Tuples
Always check (tuple? x) BEFORE (struct? x) in cond forms. Otherwise (get tuple :key) fails with "expected integer key for tuple in range [0, N), got :key". Hit us in print-value (symbol check on tuples) and eval-form struct handling.
PHM Internal Key Leakage
PHM and set internal keys (:jolt/deftype, :cnt, :buckets, :_meta, :jolt/type, :phm) leak into pairs/keys iteration. Core fns that iterate collections (core-merge, core-reduce, core-every?, core-filter) must check for set?/phm? first and use type-aware helpers (phm-to-struct, phs-seq, phm-keys, phm-entries) before generic iteration.