bootstrap: SCI core deps loading with 284/304 forms passing

reader: #?@ empty splice fix (nil→@[]), #? nil→:jolt/skip, map reader handles #_/#?@ in K/V
evaluator: unwrap-meta-name helper, deftype interns ->Name too, dot-suffix fix
core: comment/prefer-method stubs, *unchecked-math*/*clojure-version* dynamic vars
This commit is contained in:
Yogthos 2026-06-01 23:24:13 -04:00
parent cdcf569506
commit b20536d1e3
31 changed files with 1348 additions and 65 deletions

View file

@ -0,0 +1,180 @@
---
description: Jolt development workflow — build, test, special form patterns, Janet gotchas
---
# Jolt Development
## Build & Test
```bash
cd /Users/yogthos/src/jolt
jpm build # produces build/jolt
jpm test # runs all tests
janet test/foo.janet # run a single test file from project root
```
## Special Form Checklist
To add a new special form to the evaluator:
1. Add the name to `special-symbol?` in `src/jolt/evaluator.janet`
2. Add a match arm in `eval-list` (the match on `name`)
3. Add tests in `test/evaluator-test.janet`
The match arm receives `ctx`, `bindings`, and `form` (the full list). Use `(in form 1)` for first arg, etc.
**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. This means `(:ns &env)` works because the head `:ns` is a keyword, not a symbol, so it's evaluated and called as a lookup.
### Current special forms (22):
`quote`, `syntax-quote`, `unquote`, `unquote-splicing`, `do`, `if`, `def`, `defmacro`, `fn*`, `let*`, `loop*`, `recur`, `throw`, `try`, `set!`, `var`, `locking`, `instance?`, `defmulti`, `defmethod`, `deftype`, `new`, `.`
### defmacro details
- Supports optional docstring: `(defmacro name [args] body)` or `(defmacro name "doc" [args] body)`
- Implementation: `(tuple/slice form 2)` → check if first is string → adjust args-form and body start
- Implicit `&env` binding: `(put new-bindings "&env" @{})` — table, not struct (nil-safe)
- Uses `parse-arg-names` for `& rest` arg handling
### defmulti / defmethod
- `defmulti` stores the methods table on the **var** via `(put v :jolt/methods methods)`, NOT on the function
- Janet `put` on a function value fails silently
- `defmethod` retrieves methods via `(get mm-var :jolt/methods)` using `resolve-var` to get the var first
### set!
- If var doesn't exist, auto-creates it (`ns-intern`) rather than erroring
- Needed for sci's `(set! *warn-on-reflection* true)`
### defmethod (auto-create)
- If the multimethod var doesn't exist yet, auto-creates it with a dummy fn and empty methods table
- This allows sci's `defmethod print-method` to work before `defmulti print-method` is defined
### deftype
- Handles `^:meta` on type name via `with-meta` pattern
- Fields vector handles `^:meta` annotations and `^Type` hints — extracts actual symbol name
- Produces a table with `:jolt/deftype "ns.TypeName"` and keyword-keyed fields
## Janet Gotchas
- `var` declares mutable locals that can be `set` later; `def`/`let` are immutable
- `let` cannot bind to `nil` — use `(var x nil)` instead of `(let [x nil] ...)`
- `(get table key)` needs 2 args minimum — for single-arg checks use `(table :key)`
- Functions are not tables — `(put fn :prop val)` fails. Stash properties on vars
- `match` is Janet's pattern matching — no `case` or `cond` needed for simple dispatch
- Janet structs silently **drop entries with nil values**: `(struct ;[:x nil :y 1])``{:y 1}`. Use `@{}` mutable tables when nil-valued entries are needed (e.g., `&env` binding `@{}` for macro bodies)
- `match` with string patterns returns **nil** (not error) when no pattern matches. Used in `eval-list` to handle non-symbol heads cleanly — keyword heads like `:ns` fall through to default function application
- `break` in `while` does NOT return a value in Janet. Use `(var done nil)` + `(set done val)` + check pattern instead
- Janet `#{}` set literals can cause parse issues in some contexts — use `@[]` as fallback
- `(first struct)` calls `:jolt/type` method — use `(get struct :key)` instead of positional access
- Janet `(struct ;[:x nil])` silently drops the nil entry — the map becomes `{}`. Use `@{}` tables for nil-safe entries
- `(length struct)` counts key-value pairs, not keys. Use `(length (keys struct))` for key count
## Comment Handling
Comments `;` in `read-form` return `{:jolt/type :jolt/skip}` sentinel:
```janet
(= c 59) # ;
[{:jolt/type :jolt/skip} line-end])
```
`parse-next` and `parse-string` both skip over `:jolt/skip` results:
- `parse-next` uses inner `parse-next-loop` that recurses on skip
- `parse-string` recurses on skip to return next non-comment form
`read-map` checks both key AND value positions for `:jolt/skip` to skip `#_`-discarded entries.
Closing delimiters `)`, `]`, `}` in `read-form` produce explicit errors:
```janet
(= c 41) (error (string "Unmatched closing paren at " pos))
```
This prevents them from falling through to `read-symbol` which gave "Unrecognized character".
## `unwrap-meta-name` Utility
Recursively unwraps `(with-meta sym meta)` forms to extract the underlying symbol:
```janet
(defn- unwrap-meta-name [form]
(if (and (array? form) (> (length form) 0)
(struct? (in form 0))
(= :symbol ((in form 0) :jolt/type))
(= "with-meta" ((in form 0) :name)))
(unwrap-meta-name (in form 1))
form))
```
Used in: `def`, `ns` (ns name), `deftype` (type name + field names), `defmethod` (arg names).
Replaced duplicated `with-meta` unwrapping code in each of these forms.
## Bootstrap Patterns
### Class-name resolution in resolve-sym
When a simple symbol (unqualified) isn't found in current ns or clojure.core, checks for dotted class-name pattern:
`Foo.Bar.Baz` → finds last dot → ns "Foo.Bar", name "Baz" → tries ns-resolve.
This resolves symbols like `IVar` that are interned in `sci.impl.vars` but referred to unqualified from `sci.lang`.
### Reader conditionals
- `#?(:clj expr :cljs expr2)` — resolved at read time by `read-reader-conditional`
- `#?@(:clj expr :cljs expr2)` — splicing variant, wraps resolved items in `{:jolt/type :jolt/splice :items ...}`
- List/vector/set readers check for splice and flatten items
- `#_` — discard reader macro, reads next form and returns it as position only
### Core macros (in core.janet)
- `core-macro-names` returns `@{"when" true "defn" true "declare" true "defprotocol" true "extend-type" true "reify" true "fn" true "proxy" true "definterface" true "defn-" true}` — a table
- `init-core!` calls `(get (core-macro-names) name)` to check, then `(put v :macro true)`
- Order matters: macro functions must be defined BEFORE `core-bindings` map references them
### Core stubs for sci bootstrap
- `core-derive`, `core-isa?`, `core-ancestors`, `core-descendants` — minimal hierarchy
- `core-Object`, `core-Thread`, `core-ThreadLocal`, `core-IllegalStateException` — JVM class stubs
- `core-volatile!`, `core-vswap!`, `core-vreset!` — volatile (atom-like table with :val key)
- `core-defprotocol` emits `(do (def name @{}) (def method fn) ...)` — macro, returns do form
- `core-extend-type`, `core-extend-protocol`, `core-extend`, `core-reify`, `core-satisfies?`, `core-extends?`, `core-implements?`, `core-type->str` — protocol stubs
### Namespace handling
- `ns` form handles `^:meta` on ns name via `with-meta` pattern
- `def` form also handles `^:meta` on def name (extracts name-sym from `(with-meta Name meta)`)
- `require` clause in `ns` wraps each spec in `(when s ...)` for nil-safety
- `resolve-var` falls back to checking clojure.core namespace if var not found in current ns
### Bootstrap loading order
```
sci.impl.macros (4/4 ok)
sci.impl.protocols (15/17 ok)
sci.impl.utils (39/47 ok)
sci.impl.types (22/27 ok)
sci.impl.unrestrict (2/2 ok)
sci.impl.vars (28/28 ok — comment block parsed as skip)
sci.lang (10/10 ok — IVar via class-name resolve)
sci.ctx-store (6/6 ok)
sci.impl.namespaces (93/98 ok — parse crash at unmatched brace)
sci.core (60/69 ok — namespaces/*1/*2/*3/*e fail)
```
All .cljc files. #?(:clj ...) resolved at read time. #?(:cljs ...) returns nil.
### parse-arg-names
- Handles `& rest` args AND nested destructuring vectors
- When an arg is a vector (not a symbol), recurses to extract nested symbol names
## Project Structure
```
src/jolt/
types.janet — Var, Namespace, Context, symbol helpers
reader.janet — recursive descent parser for Clojure syntax
evaluator.janet — tree-walking interpreter (eval-form, eval-list, syntax-quote*)
core.janet — 95+ clojure.core functions (map, filter, reduce, etc.)
api.janet — public API: init, eval-string, eval-string*
main.janet — REPL entry point with (defn main [&])
test/
evaluator-test.janet — special form tests (22 forms tested)
reader-test.janet — parser tests (includes #?, #?@, #_)
core-test.janet — core library tests
macro-test.janet — syntax-quote and macro tests
namespace-test.janet — ns, require, in-ns tests
types-test.janet — Var and Namespace tests
api-test.janet — public API tests
bootstrap-test.janet — loads sci.impl.macros (deftime, usetime, ?)
test-load-sci.janet — loads all sci files, counts ok/fail
test-eval.janet — end-to-end sci.core/eval-string test
```