functionalscript · sergey-shandar · Aug 12, 2026 · Aug 12, 2026 · Aug 12, 2026 · Aug 12, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -20,6 +20,15 @@ history.
 
 ## Unreleased
 
+- **BREAKING CHANGES:** `fjs/media/json/parser` migrates from authored
+  TypeScript (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`) under the
+  stage-1 TypeScript-to-mjs migration, splitting `_JsonObject`,
+  `_JsonArray`, `_JsonStack`, `_StateParse`, and `_JsonState` into a
+  sibling `types.ts` — importers must use the `.f.mjs` specifier for the
+  runtime value and the `types.ts` specifier for the types. `proof.f.ts`
+  stays TypeScript for now (it depends on `fjs/media/json/module.f.ts`,
+  still unmigrated)
+  [#1499](https://github.com/functionalscript/functionalscript/pull/1499)
 - **BREAKING CHANGES:** the JSON rtti schemas `primitive`, `unknown`,
   `object`, and `array` move from `fjs/media/json/module.f.ts` to a new
   JSDoc-typed `fjs/media/json/rtti/module.f.mjs`, and the `Primitive`,

diff --git a/fjs/asn.1/module.f.mjs b/fjs/asn.1/module.f.mjs
@@ -3,10 +3,12 @@
  * helpers, length-prefixed payloads, and OID conversion via Base-128.
  *
  * @module
+ *
+ * @import { Unpacked, Vec } from '../types/bit_vec/types.ts'
+ * @import { ObjectIdentifier, Raw, Record, Sequence, SupportedRecord, _Tag } from './types.ts'
  */
 
 import { bitLength, divUp8 } from '../types/bigint/module.f.mjs'
-
 import {
     empty,
     isVec,
@@ -17,19 +19,8 @@ import {
     vec,
     vec8,
 } from '../types/bit_vec/module.f.mjs'
-
-/** @import { Unpacked, Vec } from '../types/bit_vec/types.ts' */
-
-/**
- * @import {
- *  ObjectIdentifier, Raw, Record, Sequence, SupportedRecord, _Tag,
- * } from './types.ts'
- */
-
 import { identity } from '../types/function/module.f.mjs'
-
 import { max } from '../types/function/compare/module.f.mjs'
-
 import { encode as b128encode, decode as b128decode } from '../basen/base128/module.f.mjs'
 
 //

diff --git a/fjs/asn.1/proof.f.mjs b/fjs/asn.1/proof.f.mjs
@@ -1,5 +1,5 @@
-import { empty, isVec, length, msb, uint, unpack, vec, vec8 } from '../types/bit_vec/module.f.mjs'
 /** @import { Vec } from '../types/bit_vec/types.ts' */
+import { empty, isVec, length, msb, uint, unpack, vec, vec8 } from '../types/bit_vec/module.f.mjs'
 
 import { asBase } from '../types/nominal/module.f.mjs'
 

diff --git a/fjs/basen/base128/module.f.mjs b/fjs/basen/base128/module.f.mjs
@@ -2,10 +2,11 @@
  * Base-128 encoding and decoding utilities over bit vectors.
  *
  * @module
+ *
+ * @import { Vec } from '../../types/bit_vec/types.ts'
  */
 
 import { vec8, msb, empty } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../../types/bit_vec/types.ts' */
 
 const { concat, popFront } = msb
 

diff --git a/fjs/basen/base128/proof.f.mjs b/fjs/basen/base128/proof.f.mjs
@@ -1,8 +1,7 @@
-import { empty, vec, vec8 } from '../../types/bit_vec/module.f.mjs'
 /** @import { Vec } from '../../types/bit_vec/types.ts' */
 
+import { empty, vec, vec8 } from '../../types/bit_vec/module.f.mjs'
 import { asBase } from '../../types/nominal/module.f.mjs'
-
 import { encode, decode } from './module.f.mjs'
 
 //

diff --git a/fjs/basen/base64/module.f.mjs b/fjs/basen/base64/module.f.mjs
@@ -2,13 +2,12 @@
  * Standard Base64 encoding and decoding (RFC 4648).
  *
  * @module
+ *
+ * @import { Vec } from '../../types/bit_vec/types.ts'
+ * @import { Nullable } from '../../types/nullable/types.ts'
  */
 
 import { msb, length, vec, maxLength } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../../types/bit_vec/types.ts' */
-
-/** @import { Nullable } from '../../types/nullable/types.ts' */
-
 import { baseN } from "../module.f.mjs"
 
 const alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'

diff --git a/fjs/basen/base64/proof.f.mjs b/fjs/basen/base64/proof.f.mjs
@@ -1,8 +1,7 @@
-import { assertEq } from '../../asserts/module.f.mjs'
-
-import { empty, vec, repeat, vec8, maxLength } from '../../types/bit_vec/module.f.mjs'
 /** @import { Vec } from '../../types/bit_vec/types.ts' */
 
+import { assertEq } from '../../asserts/module.f.mjs'
+import { empty, vec, repeat, vec8, maxLength } from '../../types/bit_vec/module.f.mjs'
 import { encode, decode } from './module.f.mjs'
 
 /**

diff --git a/fjs/basen/cbase32/module.f.mjs b/fjs/basen/cbase32/module.f.mjs
@@ -2,13 +2,12 @@
  * Content-addressable Base32 encoding and decoding helpers.
  *
  * @module
+ *
+ * @import { Vec } from '../../types/bit_vec/types.ts'
+ * @import { Nullable } from '../../types/nullable/types.ts'
  */
 
 import { msb, lsb, length, vec, empty } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../../types/bit_vec/types.ts' */
-
-/** @import { Nullable } from '../../types/nullable/types.ts' */
-
 import { baseN } from '../module.f.mjs'
 
 //                         0123456789abcdef

diff --git a/fjs/basen/cbase32/proof.f.mjs b/fjs/basen/cbase32/proof.f.mjs
@@ -1,8 +1,7 @@
-import { empty, vec } from '../../types/bit_vec/module.f.mjs'
 /** @import { Vec } from '../../types/bit_vec/types.ts' */
 
+import { empty, vec } from '../../types/bit_vec/module.f.mjs'
 import { cBase32ToVec, cBase32ToVec5x, vec5xToCBase32, vecToCBase32 } from './module.f.mjs'
-
 import { assertEq } from '../../asserts/module.f.mjs'
 
 //

diff --git a/fjs/basen/module.f.mjs b/fjs/basen/module.f.mjs
@@ -10,18 +10,16 @@
  * `vecToString` / `stringToVec`.
  *
  * @module
+ *
+ * @import { Vec } from '../types/bit_vec/types.ts'
+ * @import { List } from '../types/list/types.ts'
+ * @import { BaseN } from './types.ts'
  */
 
 import { msb, lsb, vec, chunkList, unpack } from '../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../types/bit_vec/types.ts' */
-
 import { fold } from '../types/list/module.f.mjs'
-/** @import { List } from '../types/list/types.ts' */
-
 import { compose } from '../types/function/module.f.mjs'
 
-/** @import { BaseN } from './types.ts' */
-
 const { unpackSplit } = msb
 
 const { tryListToVec: reversedListToVec } = lsb

diff --git a/fjs/bnf/data/module.f.mjs b/fjs/bnf/data/module.f.mjs
@@ -11,16 +11,16 @@
  * See `./types.ts` for the type-level API.
  *
  * @module
+ *
+ * @import { DataRule, Rule as FRule, Sequence as FSequence } from '../types.ts'
+ * @import { StringMap } from '../../types/object/types.ts'
+ * @import { EmptyTag, Rule, RuleSet, Sequence, Variant } from './types.ts'
  */
+
 import { stringToCodePointList } from '../../text/utf16/module.f.mjs'
 import { map, toArray } from '../../types/list/module.f.mjs'
-import {
-    oneEncode,
-} from '../module.f.mjs'
-/** @import { DataRule, Rule as FRule, Sequence as FSequence } from '../types.ts' */
+import { oneEncode } from '../module.f.mjs'
 import { definedEntries } from '../../types/object/module.f.mjs'
-/** @import { StringMap } from '../../types/object/types.ts' */
-/** @import { EmptyTag, Rule, RuleSet, Sequence, Variant } from './types.ts' */
 
 /** @typedef {StringMap<EmptyTag>} _EmptyTagMap */
 

diff --git a/fjs/bnf/data/proof.f.ts b/fjs/bnf/data/proof.f.ts
@@ -1,12 +1,14 @@
-import { stringify } from '../../media/json/module.f.ts'
+import type { RuleSet } from './types.ts'
+
 import { identity } from '../../types/function/module.f.mjs'
 import { sort } from '../../types/object/module.f.mjs'
 import { oneEncode, option, range, rangeDecode, repeat0Plus, set } from '../module.f.mjs'
-import { classic, deterministic } from '../testlib.f.ts'
 import { emptyTagMap, toData } from './module.f.mjs'
-import type { RuleSet } from './types.ts'
 import { assertEq } from '../../asserts/module.f.mjs'
 
+import { stringify } from '../../media/json/module.f.ts'
+import { classic, deterministic } from '../testlib.f.ts'
+
 export const proof = {
     rangeDecode: () => {
         const decoded1 = stringify(sort)(rangeDecode(0x000079_000087))

diff --git a/fjs/bnf/descent/module.f.mjs b/fjs/bnf/descent/module.f.mjs
@@ -14,15 +14,17 @@
  * See `./types.ts` for the type-level API.
  *
  * @module
+ *
+ * @import { TerminalRange } from '../types.ts'
+ * @import { Rule as DataRule, Sequence } from '../data/types.ts'
+ * @import { Rule as FRule } from '../types.ts'
+ * @import { AstTag, AstSequenceMeta, DescentFailure, DescentMatch, DescentMatchResult, DescentMatchRule } from './types.ts'
  */
+
 import { rangeDecode } from '../module.f.mjs'
-/** @import { TerminalRange } from '../types.ts' */
 import { contains as rangeContains } from '../../types/range/module.f.mjs'
 import { definedEntries } from '../../types/object/module.f.mjs'
 import { emptyTagMap, toData } from '../data/module.f.mjs'
-/** @import { Rule as DataRule, Sequence } from '../data/types.ts' */
-/** @import { Rule as FRule } from '../types.ts' */
-/** @import { AstTag, AstSequenceMeta, DescentFailure, DescentMatch, DescentMatchResult, DescentMatchRule } from './types.ts' */
 
 /**
  * Folds one rejected terminal into the furthest-failure record: further along

diff --git a/fjs/bnf/descent/proof.f.ts b/fjs/bnf/descent/proof.f.ts
@@ -1,13 +1,15 @@
 import type { CodePoint } from '../../text/utf16/types.ts'
+import type { DescentMatch, CodePointMeta, DescentMatchResult } from './types.ts'
+
 import { stringToCodePointList } from '../../text/utf16/module.f.mjs'
 import { map, toArray } from '../../types/list/module.f.mjs'
 import { commaJoin0Plus, option, range, repeat0Plus, set } from '../module.f.mjs'
-import { deterministic } from '../testlib.f.ts'
 import { emptyTagMap, toData } from '../data/module.f.mjs'
 import { descentParser } from './module.f.mjs'
-import type { DescentMatch, CodePointMeta, DescentMatchResult } from './types.ts'
 import { assertEq, assertNotNullish } from '../../asserts/module.f.mjs'
 
+import { deterministic } from '../testlib.f.ts'
+
 const mapCodePoint = (cp: CodePoint): CodePointMeta<unknown> => [cp, undefined]
 
 // The code point of a one-character string, for expectations that would

diff --git a/fjs/bnf/ll1/module.f.mjs b/fjs/bnf/ll1/module.f.mjs
@@ -11,19 +11,21 @@
  * See `./types.ts` for the type-level API.
  *
  * @module
+ *
+ * @import { Properties } from '../../types/range_map/types.ts'
+ * @import { StringSet } from '../../types/string_set/types.ts'
+ * @import { EmptyTag, RuleSet } from '../data/types.ts'
+ * @import { Rule as FRule } from '../types.ts'
+ * @import { AstSequence, AstTag, Match, MatchResult, MatchRule, Remainder, _Dispatch, _DispatchMap, _DispatchResult, _DispatchRule } from './types.ts'
  */
+
 import { strictEqual } from '../../types/function/operator/module.f.mjs'
 import { toArray } from '../../types/list/module.f.mjs'
 import { rangeMap } from '../../types/range_map/module.f.mjs'
-/** @import { Properties } from '../../types/range_map/types.ts' */
 import { contains, set } from '../../types/string_set/module.f.mjs'
-/** @import { StringSet } from '../../types/string_set/types.ts' */
 import { rangeDecode } from '../module.f.mjs'
 import { definedEntries } from '../../types/object/module.f.mjs'
 import { emptyTagMap, toData } from '../data/module.f.mjs'
-/** @import { EmptyTag, RuleSet } from '../data/types.ts' */
-/** @import { Rule as FRule } from '../types.ts' */
-/** @import { AstSequence, AstTag, Match, MatchResult, MatchRule, Remainder, _Dispatch, _DispatchMap, _DispatchResult, _DispatchRule } from './types.ts' */
 
 /** @type {Properties<_DispatchResult>} */
 const dispatchProps = {

diff --git a/fjs/bnf/ll1/proof.f.ts b/fjs/bnf/ll1/proof.f.ts
@@ -1,13 +1,15 @@
+import type { RuleSet } from '../data/types.ts'
+import type { MatchResult } from './types.ts'
+
 import { stringToCodePointList } from '../../text/utf16/module.f.mjs'
 import { toArray } from '../../types/list/module.f.mjs'
 import { commaJoin0Plus, option, range, repeat0Plus, set } from '../module.f.mjs'
-import { deterministic } from '../testlib.f.ts'
 import { toData } from '../data/module.f.mjs'
-import type { RuleSet } from '../data/types.ts'
 import { dispatchMap, parser, parserRuleSet } from './module.f.mjs'
-import type { MatchResult } from './types.ts'
 import { assertEq } from '../../asserts/module.f.mjs'
 
+import { deterministic } from '../testlib.f.ts'
+
 export const proof = {
     dispatch: [
         () => {

diff --git a/fjs/bnf/module.f.mjs b/fjs/bnf/module.f.mjs
@@ -6,17 +6,17 @@
  * See `./types.ts` for the type-level API.
  *
  * @module
+ *
+ * @import { Tuple } from '../types/array/types.ts'
+ * @import { TerminalRange, Sequence, Rule, RangeVariant, None, Option, Repeat0Plus, Repeat1Plus, Join1Plus, Repeat } from './types.ts'
  */
 
-/** @import { Tuple } from '../types/array/types.ts' */
-
 import { codePointListToString, stringToCodePointList } from '../text/utf16/module.f.mjs'
 import { definedValues } from '../types/object/module.f.mjs'
 import { isTuple } from '../types/array/module.f.mjs'
 import { map, toArray, repeat as listRepeat } from '../types/list/module.f.mjs'
 import { contains } from '../types/range/module.f.mjs'
 import { assert } from '../asserts/module.f.mjs'
-/** @import { TerminalRange, Sequence, Variant, DataRule, LazyRule, Rule, RangeVariant, None, Option, Repeat0Plus, Repeat1Plus, Join1Plus, Join0Plus, Repeat } from './types.ts' */
 
 // Internals:
 

diff --git a/fjs/bnf/proof.f.ts b/fjs/bnf/proof.f.ts
@@ -1,5 +1,6 @@
+import type { Rule } from './types.ts'
+
 import { assert, assertEq } from '../asserts/module.f.mjs'
-import { classic, deterministic } from './testlib.f.ts'
 import {
     rangeEncode,
     str,
@@ -10,7 +11,8 @@ import {
     oneEncode,
     repeat1Plus,
 } from './module.f.mjs'
-import type { Rule } from './types.ts'
+
+import { classic, deterministic } from './testlib.f.ts'
 
 export const proof = {
     test: () => {

diff --git a/fjs/bnf/testlib.f.ts b/fjs/bnf/testlib.f.ts
@@ -1,3 +1,5 @@
+import type { Rule } from './types.ts'
+
 import {
     commaJoin0Plus,
     none,
@@ -9,7 +11,6 @@ import {
     set,
     unicodeMax,
 } from './module.f.mjs'
-import type { Rule } from './types.ts'
 
 export const classic = (): Rule => {
 

diff --git a/fjs/bnf/token_symbol/module.f.mjs b/fjs/bnf/token_symbol/module.f.mjs
@@ -9,11 +9,13 @@
  * See `./types.ts` for the `Encoding<T>` type-level API.
  *
  * @module
+ *
+ * @import { Encoding } from './types.ts'
  */
+
 import { assert } from '../../asserts/module.f.mjs'
 import { fromUndefined } from '../../types/nullable/module.f.mjs'
 import { eof, rangeDecode, unicodeRange } from '../module.f.mjs'
-/** @import { Encoding } from './types.ts' */
 
 const [, unicodeLast] = rangeDecode(unicodeRange)
 

diff --git a/fjs/bnf/types.ts b/fjs/bnf/types.ts
@@ -3,6 +3,7 @@
  *
  * @module
  */
+
 import type { StringMap } from '../types/object/types.ts'
 
 /**

diff --git a/fjs/cas/cli/module.f.mjs b/fjs/cas/cli/module.f.mjs
@@ -2,18 +2,19 @@
  * CAS CLI command handlers.
  *
  * @module
+ *
+ * @import { All, Read, Write, WriteFile } from '../../effects/node/types.ts'
+ * @import { Commands } from '../../cli/types.ts'
+ * @import { MemOp } from '../../effects/memory/types.ts'
+ * @import { FileCasOperation } from '../types.ts'
  */
 
 import { sha256 } from '../../crypto/sha2/module.f.mjs'
 import { cBase32ToVec, vecToCBase32 } from '../../basen/cbase32/module.f.mjs'
 import { forEachStep, pure, step } from '../../effects/module.f.mjs'
 import { errorExit, log, writeFromStream } from '../../effects/node/module.f.mjs'
-/** @import { All, Read, Write, WriteFile } from '../../effects/node/types.ts' */
 import { dispatch } from '../../cli/module.f.mjs'
-/** @import { Commands } from '../../cli/types.ts' */
-/** @import { MemOp } from '../../effects/memory/types.ts' */
 import { casAddFile, fileCas } from '../module.f.mjs'
-/** @import { FileCasOperation } from '../types.ts' */
 
 /** @type {Commands<FileCasOperation | WriteFile | Write | All | MemOp | Read>} */
 export const commands = [

diff --git a/fjs/cas/cli/proof.f.mjs b/fjs/cas/cli/proof.f.mjs
@@ -1,8 +1,9 @@
+/** @import { NodeProgramOptions } from '../../effects/node/types.ts' */
+
 import { commands } from './module.f.mjs'
 import { computeSync, sha256 } from '../../crypto/sha2/module.f.mjs'
 import { maxLength, vec, vec8 } from '../../types/bit_vec/module.f.mjs'
 import { defaultNodeProgramOptions, emptyState, virtual } from '../../effects/node/virtual/module.f.mjs'
-/** @import { NodeProgramOptions } from '../../effects/node/types.ts' */
 import { dispatch } from '../../cli/module.f.mjs'
 import { vecToCBase32 } from '../../basen/cbase32/module.f.mjs'
 import { assert, assertEq } from '../../asserts/module.f.mjs'
-Original file line number
+Diff line change
@@ Expand Up / @@ -3,6 +3,7 @@ @@
      *
      * @module
      */
     import type { StringMap } from '../types/object/types.ts'
     /**
@@ Expand Down @@