functionalscript · sergey-shandar · Aug 11, 2026 · Aug 10, 2026 · Aug 10, 2026 · Aug 10, 2026
diff --git a/AGENTS.md b/AGENTS.md
@@ -212,7 +212,7 @@ new uncovered branch.
 
 To prove that a type resolves to what you claim, write
 `type _Name = Assert<Equal<Actual, Expected>>` — `Assert` from
-`fjs/asserts/module.f.mjs`, `Equal` from `fjs/types/ts/module.f.mjs`. A wrong
+`fjs/asserts/types.ts`, `Equal` from `fjs/types/ts/types.ts`. A wrong
 claim is then a compile error (TS2344, "Type 'false' does not satisfy the
 constraint 'true'"), and the check costs nothing at runtime.
 

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -20,6 +20,12 @@ history.
 
 ## Unreleased
 
+- **BREAKING CHANGES:** every public type exported by an authored `.f.mjs`
+  module moves to a sibling `types.ts` (31 modules, including `asserts`,
+  `types/list`, `types/bit_vec`, `types/result`, `text`, `crypto/sha2`) —
+  importers of these types must use the `types.ts` specifier. The runtime-empty
+  `fjs/types/option/module.f.mjs` becomes `fjs/types/option/types.ts`
+  [#1483](https://github.com/functionalscript/functionalscript/pull/1483)
 - `fjs/types/nullable/proof.f.ts`, `fjs/types/range/proof.f.ts`,
   `fjs/types/function/proof.f.ts`, `fjs/types/result/proof.f.ts`, and
   `fjs/types/function/compare/proof.f.ts` migrate to `proof.f.mjs` under

diff --git a/fjs/asn.1/module.f.mjs b/fjs/asn.1/module.f.mjs
@@ -18,7 +18,13 @@ import {
     vec8,
 } from '../types/bit_vec/module.f.mjs'
 
-/** @import { Unpacked, Vec } 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'
 
@@ -57,12 +63,6 @@ const tagNumberMask = 0b000_11111n
  * @typedef {readonly[_ClassPc, bigint]} _ParsedTag
  */
 
-/**
- * ASN.1 tag number.
- *
- * @typedef {bigint} _Tag
- */
-
 /** @type {([classPc, number]: _ParsedTag) => Vec} */
 const parsedTagEncode = ([classPc, number]) => {
     const [firstByteNumber, rest] = number < tagNumberMask
@@ -179,12 +179,6 @@ const lenDecode = v => {
 
 // raw
 
-/**
- * Raw ASN.1 TLV tuple.
- *
- * @typedef {readonly [_Tag, Vec]} Raw
- */
-
 /**
  * Encodes a raw ASN.1 TLV tuple into a bit vector.
  *
@@ -265,12 +259,6 @@ export const decodeOctetString = v => v
 
 // object identifier
 
-/**
- * ASN.1 OBJECT IDENTIFIER components.
- *
- * @typedef {readonly bigint[]} ObjectIdentifier
- */
-
 /**
  * Encodes an OBJECT IDENTIFIER value.
  *
@@ -313,12 +301,6 @@ export const decodeObjectIdentifier = v => {
 
 // sequence
 
-/**
- * ASN.1 ordered collection of records.
- *
- * @typedef {readonly Record[]} Sequence
- */
-
 /**
  * @param {(vec: readonly Vec[]) => readonly Vec[]} map
  * @return {(...records: Sequence) => Vec}
@@ -343,12 +325,6 @@ export const decodeSequence = v => decodeAll(decode)(v)
 
 // set
 
-/**
- * ASN.1 SET represented as a sequence of records.
- *
- * @typedef {Sequence} Set
- */
-
 /**
  * Encodes a SET payload with canonical byte ordering.
  *
@@ -364,43 +340,6 @@ export const encodeSet =
  */
 export const decodeSet = decodeSequence
 
-// Record
-
-/**
- * Supported ASN.1 record variants.
- *
- * @typedef {|
- *  readonly[typeof boolean, boolean] |
- *  readonly[typeof integer, bigint] |
- *  readonly[typeof octetString, Vec] |
- *  readonly[typeof objectIdentifier, ObjectIdentifier] |
- *  readonly[typeof constructedSequence, Sequence] |
- *  readonly[typeof constructedSet, Set]
- * } SupportedRecord
- */
-
-// Alternative:
-//
-// export type SupportedRecord =
-//     | boolean
-//     | bigint                                                    // integer
-//     | { tag: typeof octetString, value: Vec }
-//     | { tag: typeof objectIdentifier, value: ObjectIdentifier }
-//     | readonly Record[]                                         // sequence
-//     | { tag: typeof constructedSet, value: readonly Record[] }
-//
-// export type UnsupportedRecord =
-//     | { tag: null, value: Vec }
-
-/**
- * For unsupported tags, we just store the raw value including the tag and length,
- * so that it can be re-encoded without loss of information.
- *
- * @typedef {Vec} UnsupportedRecord
- */
-
-/** @typedef {SupportedRecord | UnsupportedRecord} Record */
-
 // encode
 
 /** @type {(_: SupportedRecord) => Vec} */

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/module.f.mjs' */
+/** @import { Vec } from '../types/bit_vec/types.ts' */
 
 import { asBase } from '../types/nominal/module.f.mjs'
 
@@ -18,7 +18,7 @@ import {
     encodeObjectIdentifier,
     decodeObjectIdentifier,
 } from './module.f.mjs'
-/** @import { SupportedRecord, ObjectIdentifier } from './module.f.mjs' */
+/** @import { SupportedRecord, ObjectIdentifier } from './types.ts' */
 
 import { assert, assertEq } from '../asserts/module.f.mjs'
 

diff --git a/fjs/asn.1/todo/65z-asn1-tag-codec-table.md b/fjs/asn.1/todo/65z-asn1-tag-codec-table.md
@@ -82,7 +82,7 @@ declaration site per (tag, encode, decode) triple.
 
 ### Caveats
 
-- `SupportedRecord` is a discriminated union keyed by tag (`fjs/asn.1/module.f.mjs:272-278`),
+- `SupportedRecord` is a discriminated union keyed by tag (`fjs/asn.1/types.ts:45-51`),
   so the codec values are heterogeneously typed. The table approach loses the
   per-branch payload typing that the switch currently gives `recordToRaw`. A
   small per-tag helper that types `encode` against the union branch may be

diff --git a/fjs/asn.1/types.ts b/fjs/asn.1/types.ts
@@ -0,0 +1,72 @@
+/**
+ * Types for ASN.1 BER/DER encoding and decoding over bit vectors.
+ *
+ * @module
+ */
+
+import type { Vec } from '../types/bit_vec/types.ts'
+import type {
+    boolean as booleanTag,
+    constructedSequence,
+    constructedSet,
+    integer,
+    objectIdentifier,
+    octetString,
+} from './module.f.mjs'
+
+/**
+ * ASN.1 tag number.
+ */
+export type _Tag = bigint
+
+/**
+ * Raw ASN.1 TLV tuple.
+ */
+export type Raw = readonly [_Tag, Vec]
+
+/**
+ * ASN.1 OBJECT IDENTIFIER components.
+ */
+export type ObjectIdentifier = readonly bigint[]
+
+/**
+ * ASN.1 ordered collection of records.
+ */
+export type Sequence = readonly Record[]
+
+/**
+ * ASN.1 SET represented as a sequence of records.
+ */
+export type Set = Sequence
+
+/**
+ * Supported ASN.1 record variants.
+ */
+export type SupportedRecord =
+    | readonly [typeof booleanTag, boolean]
+    | readonly [typeof integer, bigint]
+    | readonly [typeof octetString, Vec]
+    | readonly [typeof objectIdentifier, ObjectIdentifier]
+    | readonly [typeof constructedSequence, Sequence]
+    | readonly [typeof constructedSet, Set]
+
+// Alternative:
+//
+// export type SupportedRecord =
+//     | boolean
+//     | bigint                                                    // integer
+//     | { tag: typeof octetString, value: Vec }
+//     | { tag: typeof objectIdentifier, value: ObjectIdentifier }
+//     | readonly Record[]                                         // sequence
+//     | { tag: typeof constructedSet, value: readonly Record[] }
+//
+// export type UnsupportedRecord =
+//     | { tag: null, value: Vec }
+
+/**
+ * For unsupported tags, we just store the raw value including the tag and
+ * length, so that it can be re-encoded without loss of information.
+ */
+export type UnsupportedRecord = Vec
+
+export type Record = SupportedRecord | UnsupportedRecord
diff --git a/fjs/asserts/module.f.mjs b/fjs/asserts/module.f.mjs
@@ -33,15 +33,6 @@ export const assertEq = (...x) => {
     assert(a === b, x)
 }
 
-/**
- * Compile-time-only check: a type resolves only if it is exactly `true`.
- * Used to assert type-level properties without any runtime cost, e.g.
- * `type _ = Assert<Equal<A, B>>`.
- *
- * @template {true} T
- * @typedef {T} Assert
- */
-
 /**
  * Asserts that `a` is neither `null` nor `undefined` and returns it,
  * narrowed to `T`.

diff --git a/fjs/asserts/types.ts b/fjs/asserts/types.ts
@@ -0,0 +1,12 @@
+/**
+ * Type-level assertion helpers.
+ *
+ * @module
+ */
+
+/**
+ * Compile-time-only check: a type resolves only if it is exactly `true`.
+ * Used to assert type-level properties without any runtime cost, e.g.
+ * `type _ = Assert<Equal<A, B>>`.
+ */
+export type Assert<T extends true> = T
diff --git a/fjs/basen/base128/module.f.mjs b/fjs/basen/base128/module.f.mjs
@@ -5,7 +5,7 @@
  */
 
 import { vec8, msb, empty } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } 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
@@ -1,5 +1,5 @@
 import { empty, vec, vec8 } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../../types/bit_vec/module.f.mjs' */
+/** @import { Vec } from '../../types/bit_vec/types.ts' */
 
 import { asBase } from '../../types/nominal/module.f.mjs'
 

diff --git a/fjs/basen/base64/module.f.mjs b/fjs/basen/base64/module.f.mjs
@@ -5,9 +5,9 @@
  */
 
 import { msb, length, vec, maxLength } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../../types/bit_vec/module.f.mjs' */
+/** @import { Vec } from '../../types/bit_vec/types.ts' */
 
-/** @import { Nullable } from '../../types/nullable/module.f.mjs' */
+/** @import { Nullable } from '../../types/nullable/types.ts' */
 
 import { baseN } from "../module.f.mjs"
 

diff --git a/fjs/basen/base64/proof.f.mjs b/fjs/basen/base64/proof.f.mjs
@@ -1,7 +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/module.f.mjs' */
+/** @import { Vec } from '../../types/bit_vec/types.ts' */
 
 import { encode, decode } from './module.f.mjs'
 

diff --git a/fjs/basen/cbase32/module.f.mjs b/fjs/basen/cbase32/module.f.mjs
@@ -5,9 +5,9 @@
  */
 
 import { msb, lsb, length, vec, empty } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../../types/bit_vec/module.f.mjs' */
+/** @import { Vec } from '../../types/bit_vec/types.ts' */
 
-/** @import { Nullable } from '../../types/nullable/module.f.mjs' */
+/** @import { Nullable } from '../../types/nullable/types.ts' */
 
 import { baseN } from '../module.f.mjs'
 

diff --git a/fjs/basen/cbase32/proof.f.mjs b/fjs/basen/cbase32/proof.f.mjs
@@ -1,5 +1,5 @@
 import { empty, vec } from '../../types/bit_vec/module.f.mjs'
-/** @import { Vec } from '../../types/bit_vec/module.f.mjs' */
+/** @import { Vec } from '../../types/bit_vec/types.ts' */
 
 import { cBase32ToVec, cBase32ToVec5x, vec5xToCBase32, vecToCBase32 } from './module.f.mjs'
 

diff --git a/fjs/basen/module.f.mjs b/fjs/basen/module.f.mjs
@@ -13,14 +13,14 @@
  */
 
 import { msb, lsb, vec, chunkList, unpack } from '../types/bit_vec/module.f.mjs'
-/** @import { Vec } 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/module.f.mjs' */
+/** @import { List } from '../types/list/types.ts' */
 
 import { compose } from '../types/function/module.f.mjs'
 
-/** @import { Nullable } from '../types/nullable/module.f.mjs' */
+/** @import { BaseN } from './types.ts' */
 
 const { unpackSplit } = msb
 
@@ -30,15 +30,6 @@ const { tryListToVec: reversedListToVec } = lsb
 // `baseN(...)` codec (base64, cbase32, ...).
 const chunkListMsb = chunkList(msb)
 
-/**
- * The encode/decode pair returned by {@link baseN}.
- *
- * @typedef {{
- *  readonly vecToString: (v: Vec) => string
- *  readonly stringToVec: (s: string) => Nullable<Vec>
- * }} BaseN
- */
-
 /**
  * Builds a {@link BaseN} codec for a fixed chunk width and alphabet.
  *

diff --git a/fjs/basen/types.ts b/fjs/basen/types.ts
@@ -0,0 +1,16 @@
+/**
+ * Types for the shared bit-codec factory.
+ *
+ * @module
+ */
+
+import type { Vec } from '../types/bit_vec/types.ts'
+import type { Nullable } from '../types/nullable/types.ts'
+
+/**
+ * The encode/decode pair returned by `baseN` in `./module.f.mjs`.
+ */
+export type BaseN = {
+    readonly vecToString: (v: Vec) => string
+    readonly stringToVec: (s: string) => Nullable<Vec>
+}
diff --git a/fjs/bnf/descent/module.f.ts b/fjs/bnf/descent/module.f.ts
@@ -13,7 +13,7 @@
  *
  * @module
  */
-import { type CodePoint } from '../../text/utf16/module.f.mjs'
+import type { CodePoint } from '../../text/utf16/types.ts'
 import { rangeDecode, type TerminalRange } from '../module.f.ts'
 import { contains as rangeContains } from '../../types/range/module.f.mjs'
 import { definedEntries } from '../../types/object/module.f.ts'

diff --git a/fjs/bnf/descent/proof.f.ts b/fjs/bnf/descent/proof.f.ts
@@ -1,4 +1,5 @@
-import { type CodePoint, stringToCodePointList } from '../../text/utf16/module.f.mjs'
+import type { CodePoint } from '../../text/utf16/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.ts'
 import { deterministic } from '../testlib.f.ts'