diff --git a/src/runtime/javascript/expr.ts b/src/runtime/javascript/expr.ts
index fcf3bc0f0..5b6d7b90b 100644
--- a/src/runtime/javascript/expr.ts
+++ b/src/runtime/javascript/expr.ts
@@ -11,7 +11,16 @@ export class Hypo {
 }
 
 export class Expr {
-  dummy!: string
+  constructor (n?: number) {
+    if (n != null) {
+      return new ExprLit(n)
+    }
+  }
+
+  toString (): string {
+    // TODO call showExpr
+    return this.toString()
+  }
 }
 
 export class ExprAbs extends Expr {
@@ -21,7 +30,16 @@ export class ExprApp extends Expr {
 
 }
 export class ExprLit extends Expr {
+  lit: Literal
+  constructor (l: Literal | number | bigint | string) {
+    super()
+    if (l instanceof Literal) this.lit = l
+    else this.lit = new Literal(l)
+  }
 
+  toString (): string {
+    return this.lit.toString()
+  }
 }
 export class ExprMeta extends Expr {
 
@@ -38,3 +56,14 @@ export class ExprTyped extends Expr {
 export class ExprImplArg extends Expr {
 
 }
+
+export class Literal {
+  val: number | bigint | string
+  constructor (v: number | bigint | string) {
+    this.val = v
+  }
+
+  toString (): string {
+    return this.val.toString()
+  }
+}
diff --git a/src/runtime/javascript/ffi.ts b/src/runtime/javascript/ffi.ts
index 015390c8a..89df95197 100644
--- a/src/runtime/javascript/ffi.ts
+++ b/src/runtime/javascript/ffi.ts
@@ -1,12 +1,65 @@
 /* eslint-disable @typescript-eslint/naming-convention */
+import {
+  Type,
+  // Hypo,
+  ExprAbs,
+  ExprApp,
+  ExprLit,
+  ExprMeta,
+  ExprFun,
+  ExprVar,
+  ExprTyped,
+  ExprImplArg,
+  Literal
+} from './expr'
 
+import os from 'os'
 import ffi from 'ffi-napi'
 import ref, { Pointer } from 'ref-napi'
 import ref_struct from 'ref-struct-di'
 const Struct = ref_struct(ref)
 
-export const PgfExpr = ref.refType(ref.types.void)
-export const PgfLiteral = ref.refType(ref.types.void)
+// ----------------------------------------------------------------------------
+// FFI "Types"
+
+export const voidPtr = ref.refType(ref.types.void)
+const prob_t = ref.types.float
+const size_t = ref.types.size_t
+
+const PgfDB = ref.types.void
+const PgfDBPtr = ref.refType(PgfDB)
+
+const PgfRevision = ref.refType(ref.types.void)
+export const PgfRevisionPtr = ref.refType(PgfRevision)
+
+export const PgfExn = Struct({
+  type: ref.types.int,
+  code: ref.types.int,
+  msg: ref.types.CString
+})
+export const PgfExnPtr = ref.refType(PgfExn)
+
+const PgfText = Struct({
+  size: ref.types.size_t,
+  text: ref.types.char // char[]
+})
+export const PgfTextPtr = ref.refType(PgfText)
+
+export const PgfItorPtr = ref.refType(ref.types.void)
+
+const PgfType = ref.types.void // TODO
+// const PgfTypePtr = ref.refType(PgfType)
+
+const PgfTypeHypo = ref.types.void // TODO
+const PgfTypeHypoPtr = ref.refType(PgfTypeHypo)
+
+export const PgfExpr = ref.refType(ref.types.Object)
+export const PgfLiteral = ref.refType(ref.types.Object)
+
+const PgfMetaId = ref.types.int
+
+const PgfPrintContext = ref.types.void // TODO
+const PgfPrintContextPtr = ref.refType(PgfPrintContext)
 
 const PgfUnmarshallerVtbl = Struct({
   eabs: ref.refType(ref.types.void),
@@ -23,46 +76,227 @@ const PgfUnmarshallerVtbl = Struct({
   dtyp: ref.refType(ref.types.void),
   free_ref: ref.refType(ref.types.void)
 })
-export const PgfUnmarshaller = Struct({
+const PgfUnmarshaller = Struct({
   vtbl: ref.refType(PgfUnmarshallerVtbl)
 })
+const PgfUnmarshallerPtr = ref.refType(PgfUnmarshaller)
+
+const PgfMarshallerVtbl = Struct({
+  match_lit: ref.refType(ref.types.void),
+  match_expr: ref.refType(ref.types.void),
+  match_type: ref.refType(ref.types.void)
+})
+const PgfMarshaller = Struct({
+  vtbl: ref.refType(PgfMarshallerVtbl)
+})
+const PgfMarshallerPtr = ref.refType(PgfMarshaller)
+
+// ----------------------------------------------------------------------------
+// FFI
+
+export const runtime = ffi.Library('libpgf', {
+  pgf_read_pgf: [PgfDBPtr, [ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
+  pgf_boot_ngf: [PgfDBPtr, [ref.types.CString, ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
+  pgf_read_ngf: [PgfDBPtr, [ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
+  pgf_new_ngf: [PgfDBPtr, [PgfTextPtr, ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
+  pgf_write_pgf: [ref.types.void, [ref.types.CString, PgfDBPtr, PgfRevision, PgfExnPtr]],
+
+  pgf_free_revision: [ref.types.void, [PgfDBPtr, PgfRevision]],
+
+  pgf_abstract_name: [PgfTextPtr, [PgfDBPtr, PgfRevision, PgfExnPtr]],
+  pgf_iter_categories: [ref.types.void, [PgfDBPtr, PgfRevision, PgfItorPtr, PgfExnPtr]],
+  pgf_start_cat: [PgfType, [PgfDBPtr, PgfRevision, PgfUnmarshallerPtr, PgfExnPtr]],
+  pgf_category_context: [PgfTypeHypoPtr, [PgfDBPtr, PgfRevision, PgfTextPtr, ref.refType(ref.types.size_t), PgfUnmarshallerPtr, PgfExnPtr]],
+  pgf_category_prob: [prob_t, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
+  pgf_iter_functions: [ref.types.void, [PgfDBPtr, PgfRevision, PgfItorPtr, PgfExnPtr]],
+  pgf_iter_functions_by_cat: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfItorPtr, PgfExnPtr]],
+  pgf_function_type: [PgfType, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfUnmarshallerPtr, PgfExnPtr]],
+  pgf_function_is_constructor: [ref.types.int, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
+  pgf_function_prob: [prob_t, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
+  pgf_print_expr: [PgfTextPtr, [PgfExpr, PgfPrintContextPtr, ref.types.int, PgfMarshallerPtr]],
+  pgf_read_expr: [PgfExpr, [PgfTextPtr, PgfUnmarshallerPtr]],
+  pgf_read_expr_ex: [PgfExpr, [PgfTextPtr, ref.refType(ref.types.CString), PgfUnmarshallerPtr]],
+  pgf_expr_prob: [prob_t, [PgfDBPtr, PgfRevision, PgfExpr, PgfMarshallerPtr, PgfExnPtr]],
+  pgf_print_type: [PgfTextPtr, [PgfType, PgfPrintContextPtr, ref.types.int, PgfMarshallerPtr]],
+  pgf_print_context: [PgfTextPtr, [size_t, PgfTypeHypoPtr, PgfPrintContextPtr, ref.types.int, PgfMarshallerPtr]],
+  pgf_read_type: [PgfType, [PgfTextPtr, PgfUnmarshallerPtr]],
+
+  pgf_clone_revision: [PgfRevision, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
+  pgf_commit_revision: [ref.types.void, [PgfDBPtr, PgfRevision, PgfExnPtr]],
+  pgf_checkout_revision: [PgfRevision, [PgfDBPtr, PgfTextPtr, PgfExnPtr]],
+  pgf_create_function: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfType, size_t, prob_t, PgfMarshallerPtr, PgfExnPtr]],
+  pgf_drop_function: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
+  pgf_create_category: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, size_t, PgfTypeHypoPtr, prob_t, PgfMarshallerPtr, PgfExnPtr]],
+  pgf_drop_category: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
+
+  pgf_get_global_flag: [PgfLiteral, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfUnmarshallerPtr, PgfExnPtr]],
+  pgf_set_global_flag: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfLiteral, PgfMarshallerPtr, PgfExnPtr]],
+  pgf_get_abstract_flag: [PgfLiteral, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfUnmarshallerPtr, PgfExnPtr]],
+  pgf_set_abstract_flag: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfLiteral, PgfMarshallerPtr, PgfExnPtr]]
+})
+
+// ----------------------------------------------------------------------------
+// Conversion helpers
+
+export function PgfText_AsString (txtPtr: Pointer<any>): string {
+  const txtSize = txtPtr.deref().size
+  const charPtr = ref.reinterpret(txtPtr, txtSize, ref.types.size_t.size)
+  return charPtr.toString('utf8')
+}
+
+export function PgfText_FromString (str: string): Pointer<any> {
+  const strbuf = Buffer.from(str, 'utf8')
+  const size = strbuf.length // size in bytes, not chars
+  const sizebuf = ref.alloc(ref.types.size_t, size)
+  const txtbuf = Buffer.alloc(ref.types.size_t.size + size + 1)
+  sizebuf.copy(txtbuf, 0, 0)
+  strbuf.copy(txtbuf, ref.types.size_t.size, 0)
+  return txtbuf as Pointer<void>
+}
+
+// ----------------------------------------------------------------------------
+// Un/marshalling
+
+const eabs = ffi.Callback(PgfExpr, [PgfUnmarshaller, ref.types.bool, PgfTextPtr, PgfExpr],
+  function (self, btype: boolean, name: Pointer<any>, body: Pointer<any>): Pointer<ExprAbs> {
+    return 0 as any
+  })
+
+const eapp = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfExpr, PgfExpr],
+  function (self, fun: Pointer<any>, arg: Pointer<any>): Pointer<ExprApp> {
+    return 0 as any
+  })
 
 const elit = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfLiteral],
-  function (self, lit: Pointer<any>): any { // eslint-disable-line @typescript-eslint/no-unused-vars
-    console.log('myelit')
-    console.log('  lit', lit)
-    return lit.deref()
+  function (self, lit: Pointer<any>): Pointer<ExprLit> {
+    const litObj = lit.deref() as Literal
+    const obj = new ExprLit(litObj)
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprLit>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
-const lint = ffi.Callback(PgfLiteral, [PgfUnmarshaller, ref.types.size_t, ref.refType(ref.types.uint)],
-  function (self, size: number, val: Pointer<number>): any { // eslint-disable-line @typescript-eslint/no-unused-vars
-    console.log('mylint')
-    console.log('  size', size)
-    console.log('  val', val.deref())
-    // const x: number = val.deref()
-    return val
+const emeta = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfMetaId],
+  function (self, meta: Pointer<any>): Pointer<ExprMeta> {
+    return 0 as any
   })
 
-const free_ref = ffi.Callback(ref.types.void, [PgfUnmarshaller, ref.refType(ref.types.void)],
-  function (self, x: any): void { // eslint-disable-line @typescript-eslint/no-unused-vars
-    console.log('free_ref')
+const efun = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfTextPtr],
+  function (self, name: Pointer<any>): Pointer<ExprFun> {
+    return 0 as any
   })
 
-const vtbl = new PgfUnmarshallerVtbl({
-  eabs: ref.alloc('void').ref(),
-  eapp: ref.alloc('void').ref(),
+const evar = ffi.Callback(PgfExpr, [PgfUnmarshaller, ref.types.int],
+  function (self, index: number): Pointer<ExprVar> {
+    return 0 as any
+  })
+
+const etyped = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfExpr, PgfType],
+  function (self, expr: Pointer<any>, type: Pointer<any>): Pointer<ExprTyped> {
+    return 0 as any
+  })
+
+const eimplarg = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfExpr],
+  function (self, expr: Pointer<any>): Pointer<ExprImplArg> {
+    return 0 as any
+  })
+
+// TODO get from platform/runtime
+const WORDSIZE_BITS = 64
+const WORDSIZE_BYTES = WORDSIZE_BITS / 8
+const LINT_BASE = BigInt('10000000000000000000')
+
+const lint = ffi.Callback(PgfLiteral, [PgfUnmarshaller, ref.types.size_t, ref.refType(ref.types.int)],
+  function (self, size: number, val: Pointer<number>): Pointer<Literal> {
+    let jsval: number | bigint = 0
+    if (size === 1) {
+      jsval = val.deref()
+    } else if (size > 1) {
+      jsval = BigInt(val.deref())
+      const pos = jsval >= 0
+      const vals = ref.reinterpret(val, size * WORDSIZE_BYTES)
+      for (let n = 1; n < size; n++) {
+        let thisval
+        switch (WORDSIZE_BITS) {
+          case 64:
+            thisval = BigInt((os.endianness() === 'LE') ? vals.readUInt64LE(n * WORDSIZE_BYTES) : vals.readUInt64BE(n * WORDSIZE_BYTES))
+        }
+        if (thisval == null) {
+          throw Error(`Unsupported word size: ${WORDSIZE_BITS}`)
+        }
+        jsval = (jsval * LINT_BASE) + (pos ? thisval : -thisval)
+      }
+    }
+
+    const obj = new Literal(jsval)
+    const buf = ref.alloc(ref.types.Object) as Pointer<Literal>
+    ref.writeObject(buf, 0, obj)
+    return buf
+  })
+
+const lflt = ffi.Callback(PgfLiteral, [PgfUnmarshaller, ref.types.double],
+  function (self, val: number): Pointer<Literal> {
+    const obj = new Literal(val)
+    const buf = ref.alloc(ref.types.Object) as Pointer<Literal>
+    ref.writeObject(buf, 0, obj)
+    return buf
+  })
+
+const lstr = ffi.Callback(PgfLiteral, [PgfUnmarshaller, PgfTextPtr],
+  function (self, val: Pointer<any>): Pointer<Literal> {
+    const jsval = PgfText_AsString(val)
+    const obj = new Literal(jsval)
+    const buf = ref.alloc(ref.types.Object) as Pointer<Literal>
+    ref.writeObject(buf, 0, obj)
+    return buf
+  })
+
+const dtyp = ffi.Callback(PgfType, [PgfUnmarshaller, ref.types.int, PgfTypeHypoPtr, PgfTextPtr, ref.types.int, ref.refType(PgfExpr)],
+  function (self, n_hypos: number, hypos: Pointer<any>, cat: Pointer<any>, n_exprs: number, exprs: Pointer<any>): Pointer<Type> {
+    return 0 as any
+  })
+
+const free_ref = ffi.Callback(ref.types.void, [PgfUnmarshaller, ref.refType(ref.types.Object)],
+  function (self, x: Pointer<any>): void {
+  })
+
+const un_vtbl = new PgfUnmarshallerVtbl({
+  eabs: eabs as any,
+  eapp: eapp as any,
   elit: elit as any,
-  emeta: ref.alloc('void').ref(),
-  efun: ref.alloc('void').ref(),
-  evar: ref.alloc('void').ref(),
-  etyped: ref.alloc('void').ref(),
-  eimplarg: ref.alloc('void').ref(),
+  emeta: emeta as any,
+  efun: efun as any,
+  evar: evar as any,
+  etyped: etyped as any,
+  eimplarg: eimplarg as any,
   lint: lint as any,
-  lflt: ref.alloc('void').ref(),
-  lstr: ref.alloc('void').ref(),
-  dtyp: ref.alloc('void').ref(),
+  lflt: lflt as any,
+  lstr: lstr as any,
+  dtyp: dtyp as any,
   free_ref: free_ref as any
 })
 
-export const unmarshaller = new PgfUnmarshaller({ vtbl: vtbl.ref() })
-export const marshaller = {}
+export const unmarshaller = new PgfUnmarshaller({ vtbl: un_vtbl.ref() })
+
+const match_lit = ffi.Callback(ref.types.Object, [PgfMarshaller, PgfUnmarshaller, PgfLiteral],
+  function (self, u: any, lit: any): Pointer<any> {
+    return 0 as any
+  })
+
+const match_expr = ffi.Callback(ref.types.Object, [PgfMarshaller, PgfUnmarshaller, PgfExpr],
+  function (self, u: any, expr: any): Pointer<any> {
+    return 0 as any
+  })
+
+const match_type = ffi.Callback(ref.types.Object, [PgfMarshaller, PgfUnmarshaller, PgfType],
+  function (self, u: any, type: any): Pointer<any> {
+    return 0 as any
+  })
+
+const vtbl = new PgfMarshallerVtbl({
+  match_lit: match_lit as any,
+  match_expr: match_expr as any,
+  match_type: match_type as any
+})
+
+export const marshaller = new PgfMarshaller({ vtbl: vtbl.ref() })
diff --git a/src/runtime/javascript/index.ts b/src/runtime/javascript/index.ts
index 8b2079436..d22294563 100644
--- a/src/runtime/javascript/index.ts
+++ b/src/runtime/javascript/index.ts
@@ -1,59 +1,25 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 
 import errno from './errno'
-import { Expr } from './expr'
-import { unmarshaller, PgfUnmarshaller, PgfExpr, PgfLiteral } from './ffi'
+import { Expr, ExprLit } from './expr'
+import {
+  voidPtr,
+  PgfRevisionPtr,
+  PgfItorPtr,
+  PgfTextPtr,
+  PgfExn,
+  PgfExnPtr,
+
+  PgfText_AsString,
+  PgfText_FromString,
+
+  runtime,
+  unmarshaller
+} from './ffi'
 
 import ffi from 'ffi-napi'
 import ref, { Pointer } from 'ref-napi'
-import ref_struct, { StructObject } from 'ref-struct-di'
-const Struct = ref_struct(ref)
-
-// ----------------------------------------------------------------------------
-// FFI "Types"
-
-const voidPtr = ref.refType(ref.types.void)
-const prob_t = ref.types.float
-const size_t = ref.types.size_t
-
-const PgfDB = ref.types.void
-const PgfDBPtr = ref.refType(PgfDB)
-
-const PgfRevision = ref.refType(ref.types.void)
-const PgfRevisionPtr = ref.refType(PgfRevision)
-
-const PgfExn = Struct({
-  type: ref.types.int,
-  code: ref.types.int,
-  msg: ref.types.CString
-})
-const PgfExnPtr = ref.refType(PgfExn)
-
-const PgfText = Struct({
-  size: ref.types.size_t,
-  text: ref.types.char // char[]
-})
-const PgfTextPtr = ref.refType(PgfText)
-
-const PgfItorPtr = ref.refType(ref.types.void)
-
-const PgfType = ref.types.void // TODO
-// const PgfTypePtr = ref.refType(PgfType)
-
-const PgfTypeHypo = ref.types.void // TODO
-const PgfTypeHypoPtr = ref.refType(PgfTypeHypo)
-
-// const PgfExpr = ref.types.void // TODO
-// const PgfLiteral = ref.types.void // TODO
-
-const PgfPrintContext = ref.types.void // TODO
-const PgfPrintContextPtr = ref.refType(PgfPrintContext)
-
-// const PgfUnmarshaller = ref.types.void // TODO
-const PgfUnmarshallerPtr = ref.refType(PgfUnmarshaller)
-
-const PgfMarshaller = ref.types.void // TODO
-const PgfMarshallerPtr = ref.refType(PgfMarshaller)
+import { StructObject } from 'ref-struct-di'
 
 // ----------------------------------------------------------------------------
 // TypeScript Types
@@ -72,50 +38,6 @@ class PGFError extends Error {
   }
 }
 
-// ----------------------------------------------------------------------------
-// FFI
-
-const runtime = ffi.Library('libpgf', {
-  pgf_read_pgf: [PgfDBPtr, [ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
-  pgf_boot_ngf: [PgfDBPtr, [ref.types.CString, ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
-  pgf_read_ngf: [PgfDBPtr, [ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
-  pgf_new_ngf: [PgfDBPtr, [PgfTextPtr, ref.types.CString, PgfRevisionPtr, PgfExnPtr]],
-  pgf_write_pgf: [ref.types.void, [ref.types.CString, PgfDBPtr, PgfRevision, PgfExnPtr]],
-
-  pgf_free_revision: [ref.types.void, [PgfDBPtr, PgfRevision]],
-
-  pgf_abstract_name: [PgfTextPtr, [PgfDBPtr, PgfRevision, PgfExnPtr]],
-  pgf_iter_categories: [ref.types.void, [PgfDBPtr, PgfRevision, PgfItorPtr, PgfExnPtr]],
-  pgf_start_cat: [PgfType, [PgfDBPtr, PgfRevision, PgfUnmarshallerPtr, PgfExnPtr]],
-  pgf_category_context: [PgfTypeHypoPtr, [PgfDBPtr, PgfRevision, PgfTextPtr, ref.refType(ref.types.size_t), PgfUnmarshallerPtr, PgfExnPtr]],
-  pgf_category_prob: [prob_t, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
-  pgf_iter_functions: [ref.types.void, [PgfDBPtr, PgfRevision, PgfItorPtr, PgfExnPtr]],
-  pgf_iter_functions_by_cat: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfItorPtr, PgfExnPtr]],
-  pgf_function_type: [PgfType, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfUnmarshallerPtr, PgfExnPtr]],
-  pgf_function_is_constructor: [ref.types.int, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
-  pgf_function_prob: [prob_t, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
-  pgf_print_expr: [PgfTextPtr, [PgfExpr, PgfPrintContextPtr, ref.types.int, PgfMarshallerPtr]],
-  pgf_read_expr: [PgfExpr, [PgfTextPtr, PgfUnmarshallerPtr]],
-  pgf_read_expr_ex: [PgfExpr, [PgfTextPtr, ref.refType(ref.types.CString), PgfUnmarshallerPtr]],
-  pgf_expr_prob: [prob_t, [PgfDBPtr, PgfRevision, PgfExpr, PgfMarshallerPtr, PgfExnPtr]],
-  pgf_print_type: [PgfTextPtr, [PgfType, PgfPrintContextPtr, ref.types.int, PgfMarshallerPtr]],
-  pgf_print_context: [PgfTextPtr, [size_t, PgfTypeHypoPtr, PgfPrintContextPtr, ref.types.int, PgfMarshallerPtr]],
-  pgf_read_type: [PgfType, [PgfTextPtr, PgfUnmarshallerPtr]],
-
-  pgf_clone_revision: [PgfRevision, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
-  pgf_commit_revision: [ref.types.void, [PgfDBPtr, PgfRevision, PgfExnPtr]],
-  pgf_checkout_revision: [PgfRevision, [PgfDBPtr, PgfTextPtr, PgfExnPtr]],
-  pgf_create_function: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfType, size_t, prob_t, PgfMarshallerPtr, PgfExnPtr]],
-  pgf_drop_function: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
-  pgf_create_category: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, size_t, PgfTypeHypoPtr, prob_t, PgfMarshallerPtr, PgfExnPtr]],
-  pgf_drop_category: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfExnPtr]],
-
-  pgf_get_global_flag: [PgfLiteral, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfUnmarshallerPtr, PgfExnPtr]],
-  pgf_set_global_flag: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfLiteral, PgfMarshallerPtr, PgfExnPtr]],
-  pgf_get_abstract_flag: [PgfLiteral, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfUnmarshallerPtr, PgfExnPtr]],
-  pgf_set_abstract_flag: [ref.types.void, [PgfDBPtr, PgfRevision, PgfTextPtr, PgfLiteral, PgfMarshallerPtr, PgfExnPtr]]
-})
-
 // ----------------------------------------------------------------------------
 // Helpers
 
@@ -142,22 +64,6 @@ function handleError (err: StructObject<PgfExnType>): void {
   }
 }
 
-function PgfText_AsString (txtPtr: Pointer<any>): string {
-  const txtSize = txtPtr.deref().size
-  const charPtr = ref.reinterpret(txtPtr, txtSize, ref.types.size_t.size)
-  return charPtr.toString('utf8')
-}
-
-function PgfText_FromString (str: string): Pointer<any> {
-  const strbuf = Buffer.from(str, 'utf8')
-  const size = strbuf.length // size in bytes, not chars
-  const sizebuf = ref.alloc(ref.types.size_t, size)
-  const txtbuf = Buffer.alloc(ref.types.size_t.size + size + 1)
-  sizebuf.copy(txtbuf, 0, 0)
-  strbuf.copy(txtbuf, ref.types.size_t.size, 0)
-  return txtbuf as Pointer<void>
-}
-
 // ----------------------------------------------------------------------------
 // PGF grammar object
 
@@ -185,7 +91,7 @@ export class PGFGrammar {
   getCategories (): string[] {
     const cats: string[] = []
     const callback = ffi.Callback(ref.types.void, [PgfItorPtr, PgfTextPtr, voidPtr, PgfExnPtr],
-      function (self: Pointer<any>, key: Pointer<any>, value: Pointer<any>, err: Pointer<any>) { // eslint-disable-line @typescript-eslint/no-unused-vars
+      function (self: Pointer<any>, key: Pointer<any>, value: Pointer<any>, err: Pointer<any>) {
         const k = PgfText_AsString(key)
         cats.push(k)
       })
@@ -198,7 +104,7 @@ export class PGFGrammar {
   getFunctions (): string[] {
     const funs: string[] = []
     const callback = ffi.Callback(ref.types.void, [PgfItorPtr, PgfTextPtr, voidPtr, PgfExnPtr],
-      function (self: Pointer<any>, key: Pointer<any>, value: Pointer<any>, err: Pointer<any>) { // eslint-disable-line @typescript-eslint/no-unused-vars
+      function (self: Pointer<any>, key: Pointer<any>, value: Pointer<any>, err: Pointer<any>) {
         const k = PgfText_AsString(key)
         funs.push(k)
       })
@@ -244,7 +150,7 @@ export class PGFGrammar {
     const catname = PgfText_FromString(cat)
     const funs: string[] = []
     const callback = ffi.Callback(ref.types.void, [PgfItorPtr, PgfTextPtr, voidPtr, PgfExnPtr],
-      function (self: Pointer<any>, key: Pointer<any>, value: Pointer<any>, err: Pointer<any>) { // eslint-disable-line @typescript-eslint/no-unused-vars
+      function (self: Pointer<any>, key: Pointer<any>, value: Pointer<any>, err: Pointer<any>) {
         const k = PgfText_AsString(key)
         funs.push(k)
       })
@@ -295,9 +201,7 @@ function newNGF (abstract_name: string, path?: string): PGFGrammar {
 function readExpr (str: string): Expr {
   const txt = PgfText_FromString(str)
   const expr = runtime.pgf_read_expr(txt, unmarshaller.ref())
-  console.log('expr', expr)
-
-  return new Expr()
+  return ref.readObject(expr) as Expr
 }
 
 // ----------------------------------------------------------------------------
@@ -310,5 +214,8 @@ export default {
   readNGF,
   newNGF,
 
-  readExpr
+  readExpr,
+
+  Expr,
+  ExprLit
 }
diff --git a/src/runtime/javascript/tests/basic.test.ts b/src/runtime/javascript/tests/basic.test.ts
index ae2839ce2..f2303521e 100644
--- a/src/runtime/javascript/tests/basic.test.ts
+++ b/src/runtime/javascript/tests/basic.test.ts
@@ -206,3 +206,83 @@ describe('abstract syntax', () => {
     })
   })
 })
+
+// ----------------------------------------------------------------------------
+
+describe('expressions', () => {
+  test('small integer', () => {
+    const e1 = PGF.readExpr('123')
+    const e2 = new PGF.ExprLit(123)
+    const e3 = new PGF.ExprLit(456)
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+
+  test('negative integer', () => {
+    const e1 = PGF.readExpr('-123')
+    const e2 = new PGF.ExprLit(-123)
+    const e3 = new PGF.ExprLit(-456)
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+
+  test('big integer', () => {
+    const e1 = PGF.readExpr('774763251095801167872')
+    const e2 = new PGF.ExprLit(BigInt('774763251095801167872'))
+    expect(e1).toEqual(e2)
+  })
+
+  test('negative big integer', () => {
+    const e1 = PGF.readExpr('-774763251095801167872')
+    const e2 = new PGF.ExprLit(BigInt('-774763251095801167872'))
+    expect(e1).toEqual(e2)
+  })
+
+  test('really big integer', () => {
+    const e1 = PGF.readExpr('7747632510958011678729003251095801167999')
+    const e2 = new PGF.ExprLit(BigInt('7747632510958011678729003251095801167999'))
+    const e3 = new PGF.ExprLit(BigInt('7747632510958011678729003251095801167990'))
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+
+  test('negative really big integer', () => {
+    const e1 = PGF.readExpr('-7747632510958011678729003251095801167999')
+    const e2 = new PGF.ExprLit(BigInt('-7747632510958011678729003251095801167999'))
+    const e3 = new PGF.ExprLit(BigInt('-7747632510958011678729003251095801167990'))
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+
+  test('float', () => {
+    const e1 = PGF.readExpr('3.142')
+    const e2 = new PGF.ExprLit(3.142)
+    const e3 = new PGF.ExprLit(2.014)
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+
+  test('negative float', () => {
+    const e1 = PGF.readExpr('-3.142')
+    const e2 = new PGF.ExprLit(-3.142)
+    const e3 = new PGF.ExprLit(-2.014)
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+
+  test('string', () => {
+    const e1 = PGF.readExpr('"abc"')
+    const e2 = new PGF.ExprLit('abc')
+    const e3 = new PGF.ExprLit('def')
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+
+  test('string unicode', () => {
+    const e1 = PGF.readExpr('"açġħ"')
+    const e2 = new PGF.ExprLit('açġħ')
+    const e3 = new PGF.ExprLit('acgh')
+    expect(e1).toEqual(e2)
+    expect(e1).not.toEqual(e3)
+  })
+})
diff --git a/src/runtime/javascript/tsconfig.json b/src/runtime/javascript/tsconfig.json
index 663573160..ef83dd09b 100644
--- a/src/runtime/javascript/tsconfig.json
+++ b/src/runtime/javascript/tsconfig.json
@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "target": "es5",
+    "target": "ES2015",
     "module": "commonjs",
     "rootDir": "./",
     "moduleResolution": "node",
diff --git a/src/runtime/typescript/MOVED.md b/src/runtime/typescript/MOVED.md
deleted file mode 100644
index 3648aa226..000000000
--- a/src/runtime/typescript/MOVED.md
+++ /dev/null
@@ -1,7 +0,0 @@
-# Project moved
-
-The GF TypeScript runtime has been moved to the repository:
-<https://github.com/GrammaticalFramework/gf-typescript>
-
-If you are looking for an updated version of the JavaScript runtime,
-you should also look there.