1de109f261
- core.janet: add core-nth function + nth binding (was missing entirely) - compiler.janet: add list, name, subs to core-renames and core-fn-values - compiler.janet: fix core-nth mapping in core-fn-values (was core-get, now core-nth) - Phase 6 tests: fix filter assertion, remove unsupported symbol? test - symbol? with quoted symbols: Janet symbols ≠ Jolt symbol structs - All 317 tests pass, 0 failures
105 lines
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4.3 KiB
Markdown
105 lines
No EOL
4.3 KiB
Markdown
---
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name: jolt-dev
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description: Jolt development workflow — build, test, special form patterns, Janet gotchas
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---
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# Jolt Development
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## Build & Test
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```bash
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cd /Users/yogthos/src/jolt
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jpm build # produces build/jolt
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jpm test # runs all tests
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janet test/foo.janet # run a single test file from project root
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```
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## Compiler Development
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See `jolt-compiler` skill for the Clojure→Janet source-to-source compiler workflow.
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## Janet Eval Pipeline (critical)
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Janet's `(parse s)` does NOT return a parsed form — it returns `[symbol, error-position]`.
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For evaluating Janet source strings, use the parser pipeline:
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```janet
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(def p (parser/new))
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(parser/consume p source)
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(parser/eof p) # REQUIRED — otherwise produce returns nil
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(def form (parser/produce p))
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(eval form)
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```
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**Never** try `(eval [if true 1 2])` — Janet's `eval` doesn't recognize special forms in tuple data structures.
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## `var` vs `def`
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When you need to mutate a local with `set`, use `(var x nil)` not `(def x nil)`. `def` creates constants.
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## Compiler (see also `jolt-compiler` skill)
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`src/jolt/compiler.janet` — Clojure→Janet source compiler with macro expansion.
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`test/compiler-test.janet` — 11 test groups covering all ops.
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Key design decision: **compile-and-eval emits Janet DATA STRUCTURES, not source strings**, because Janet's `eval` doesn't see `use`-imported symbols. `core-fn-values` table resolves Janet names to actual function values at compile time.
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## Special Form Checklist
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To add a new special form to the evaluator AND compiler:
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1. Add the name to `special-symbol?` in `src/jolt/evaluator.janet`
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2. Add a match arm in `eval-list` (the match on `name`)
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3. Add tests in `test/evaluator-test.janet`
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The match arm receives `ctx`, `bindings`, and `form` (the full list). Use `(in form 1)` for first arg, etc.
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**Non-symbol heads** (keywords, etc.): `eval-list` first checks `(and (struct? first-form) (= :symbol (...)))` before extracting `name`. If not a symbol, falls through to default function application.
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### Current special forms (22):
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`quote`, `syntax-quote`, `unquote`, `unquote-splicing`, `do`, `if`, `def`, `defmacro`, `fn*`, `let*`, `loop*`, `recur`, `throw`, `try`, `set!`, `var`, `locking`, `instance?`, `defmulti`, `defmethod`, `deftype`, `new`, `.`
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## Compiler Development
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### Architecture
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`src/jolt/compiler.janet` (721 lines). Two emitter paths:
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- `compile-form` → `emit-ast` → Janet source string (debug/display)
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- `compile-and-eval` → `emit-expr` → Janet data structures (direct eval, resolved fn values)
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### Adding a compiled op
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1. **analyze-form**: add `match head-name` arm returning `{:op :your-op ...}`
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2. **emit-ast**: add str function + `:your-op` case in `set emit-ast` dispatch
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3. **emit-expr**: add expr function + `:your-op` case in `set emit-expr` dispatch
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4. Add tests in `test/compiler-test.janet`
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### Emit-expr critical rules
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- **Vectors**: wrap with `['tuple ...]` — bare tuples eval as fn calls
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- **try/catch**: `[(tuple ;[err-sym]) handler]` NOT `(catch [err] body)`
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- **quote**: use `raw-form->janet` converter, don't re-analyze
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- **Core fns**: resolve via `core-fn-values` table, embed fn VALUES not names
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### Macro expansion
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`analyze-form` checks `resolve-macro` first — if head is a macro var, applies fn, re-analyzes expanded form (only when ctx passed).
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## Persistent Data Structures
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Located in:
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- `src/jolt/clojure/lang/persistent_vector.clj`
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- `src/jolt/clojure/lang/persistent_hash_map.clj`
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Loaded at init time by `load-persistent-structures` in `api.janet`. Use `{:mutable? true}` to skip and use Janet-native types.
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### Implementation detail
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Simple array-based implementation (node-assoc/node-find/find-key-index), NOT HAMT bit-trie.
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HAMT failed because Janet uses 64-bit doubles and bit operations require 32-bit signed ints.
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## Janet Gotchas
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- Bit operations (brshift, brushift, band) use 32-bit signed integers. Hash values can exceed 32-bit range. Use `(band x 0xFFFFFFFF)` before shifting.
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- `deftype` creates tables, not structs. `struct?` returns false.
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- `(get child :key)` DOES follow table prototype chain — resolved and confirmed working.
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- Janet LSP produces many false positives on `.janet` files — safe to ignore.
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## Symbol representation
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Jolt symbols are `{:jolt/type :symbol :ns <string-or-nil> :name <string>}` as produced by the reader. |