a8c453183f
- resolve-macro: resolve symbols to macro vars via ctx - Macro expansion in analyze-form: detects macro heads, expands, re-analyzes - compile-ast: emits Janet data structures with resolved core fn values - compile-and-eval uses compile-ast (no source parse roundtrip) - eval-string routes macros through compiler (expanded at analyze time) - Fix - mapping: core-sub (core-- doesn't exist) - All 317 tests pass + 6 new Phase 4 macro tests
97 lines
3.5 KiB
Markdown
97 lines
3.5 KiB
Markdown
---
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triggers:
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- "compile jolt"
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- "jolt compiler"
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- "Clojure to Janet compilation"
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- "add new op to compiler"
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- "fix compiler"
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---
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# Jolt Compiler
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Source-to-source Clojure→Janet compiler. Two-phase: analyze-form (classify + macro expand) → emit-ast (generate).
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## Architecture
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```
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Clojure form → analyze-form [form bindings ctx] → AST {:op ...}
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↓ (if head = macro var)
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expand → re-analyze expanded form
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↓
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emit-ast (source string) or emit-expr (data structure)
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```
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Three public entry points:
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- `(compile-form form &opt ctx)` → Janet source string (debug/display)
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- `(compile-ast form &opt ctx)` → Janet data structure (for eval)
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- `(compile-and-eval form ctx)` → compile-ast + eval
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## Why data structures, not source strings
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Janet's `eval` does NOT have access to `use`-imported symbols from the calling file. `(eval "(core-inc 1)")` fails with "unknown symbol core-inc". The fix: emit Janet tuples where function VALUES are embedded: `[core-inc 1]`.
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```
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core-fn-values table: "core-inc" → core-inc (the actual function)
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emit-core-symbol-expr → (get core-fn-values janet-name)
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```
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Source-to-source (`compile-form` + `emit-ast`) still exists for debugging but is NOT used by `compile-and-eval`.
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## Macro expansion
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`analyze-form` checks whether the head symbol of a list resolves to a macro var before dispatching to special form handling:
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1. Look up symbol in current ns → core ns via `resolve-macro`
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2. If `var-macro?` is true, call `(var-get macro-var)` to get the fn
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3. `(apply macro-fn (tuple/slice form 1))` to expand
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4. `(analyze-form expanded ...)` to re-analyze the result
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Macros expand at analyze time, before emission. `defn` expands to `(def name (fn* ...))`, `when` to `(if test (do ...) nil)`, etc.
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## Symbol classification (in analyze-form)
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Order: qualified ns → local binding → core-symbol → bare symbol
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```
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(if (form :ns) → :qualified-symbol
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(get bindings name) → :local
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(get core-renames name) → :core-symbol
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→ :symbol)
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```
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core-renames MUST match actual fn names: `"-"` → `"core-sub"` (not `"core--"`), `"not"` → `"core-not"`. Verify against `core.janet` bindings.
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## core-fn-values
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Maps Janet string names to actual function values. Must be kept in sync with core-renames. When adding a new core fn, update BOTH tables.
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Functions that need special mapping (name differs):
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- `"apply"` → `apply` (Janet built-in)
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- `"-"` → `"core-sub"` (not `core--`)
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- `"some"` → `core-some?` (shared with `core-some?`)
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- `"pr-str"` → `core-str` (alias)
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- `"nth"` → `core-get` (alias)
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## Stateful forms (must use interpreter, NOT compiler)
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These forms modify context state and cannot be compiled:
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- `defmacro`, `ns`, `deftype`, `defmulti`, `defmethod`, `require`, `in-ns`
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Note: `def` IS handled by the compiler (compiles to Janet `def`).
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## Adding a new op
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1. Add `analyze-form` match arm for the special form
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2. Add `emit-ast` match arm (source string path)
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3. Add `emit-expr` match arm (data structure path)
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4. Add `core-renames` entry if it's a core fn (name → Janet string name)
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5. Add `core-fn-values` entry (Janet string name → actual fn value)
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6. Add tests in `test/compiler-test.janet`
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## Test patterns
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- Source output tests: `(assert (= "(expected)" (compile-str "(input)")) "label")`
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- Round-trip tests: `(assert (= val (compile-eval-str "(input)")) "label")`
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- Compile flag tests: `(eval-string ctx "(input)")` with `{:compile? true}`
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Run: `janet test/compiler-test.janet` or `jpm test`
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