Merge branch 'majestic' of github.com:GrammaticalFramework/gf-core into majestic

src/runtime/c/README.md

@@ -2,7 +2,9 @@
 
 ## Requirements
 
-Required system packages (Debian/Ubuntu):
+### Debian/Ubuntu
+
+Required system packages (`apt install ...`):
 ```
 autoconf
 automake
@@ -11,6 +13,11 @@ make
 g++
 ```
 
+### macOS
+
+- Install XCode from App Store
+- Install XCode command line tools: `xcode-select --install`
+
 ## Installation
 
 Installing the runtime (puts libraries in `/usr/local/lib`):

src/runtime/javascript/README.md

@@ -30,3 +30,12 @@ npm run build
 ```
 npm run test
 ```
+
+## Known issues
+
+There is a known issue with random crashes with Node 14 and 16 on macOS. See here:
+- https://github.com/nodejs/node/issues/32463
+- https://github.com/node-ffi-napi/node-ffi-napi/issues/97
+- https://github.com/node-ffi-napi/ref-napi/issues/47
+
+It seems to work with Node 12 on macOS, as well as on other platforms.

src/runtime/javascript/constants.ts

@@ -0,0 +1,39 @@
+// Untested!
+import os from 'os'
+
+export const BE: boolean = os.endianness() === 'BE'
+
+export let WORDSIZE_BITS: number
+switch (process.arch) {
+  case 'arm':
+  case 'ia32':
+  case 'ppc':
+  case 's390':
+  case 'x32':
+    WORDSIZE_BITS = 32
+    break
+
+  case 'arm64':
+  case 'mips':
+  case 'mipsel':
+  case 'ppc64':
+  case 's390x':
+  case 'x64':
+    WORDSIZE_BITS = 64
+    break
+
+  default:
+    throw Error(`Unknown architecture: ${process.arch}`)
+}
+
+export const WORDSIZE_BYTES = WORDSIZE_BITS / 8
+
+export let LINT_BASE: bigint
+
+switch (WORDSIZE_BITS) {
+  case 64: LINT_BASE = BigInt('10000000000000000000'); break
+  case 32: LINT_BASE = BigInt('1000000000'); break
+  case 16: LINT_BASE = BigInt('10000'); break
+  case 8: LINT_BASE = BigInt('100'); break
+  default: throw Error(`Unsupported word size: ${WORDSIZE_BITS}`)
+}

src/runtime/javascript/expr.ts

@@ -1,7 +1,13 @@
 export class Type {
-  hypos!: Hypo[]
-  name!: string
-  exprs!: Expr[]
+  hypos: Hypo[]
+  name: string
+  exprs: Expr[]
+
+  constructor (hs: Hypo[], n: string, es: Expr[]) {
+    this.hypos = hs
+    this.name = n
+    this.exprs = es
+  }
 }
 
 export class Hypo {
@@ -11,6 +17,7 @@ export class Hypo {
 }
 
 export class Expr {
+  // TODO overload
   constructor (n?: number) {
     if (n != null) {
       return new ExprLit(n)
@@ -24,13 +31,32 @@ export class Expr {
 }
 
 export class ExprAbs extends Expr {
+  bind_type: boolean
+  name: string
+  body: Expr
 
+  constructor (bt: boolean, n: string, b: Expr) {
+    super()
+    this.bind_type = bt
+    this.name = n
+    this.body = b
+  }
 }
+
 export class ExprApp extends Expr {
+  fun: Expr
+  arg: Expr
 
+  constructor (f: Expr, a: Expr) {
+    super()
+    this.fun = f
+    this.arg = a
+  }
 }
+
 export class ExprLit extends Expr {
   lit: Literal
+
   constructor (l: Literal | number | bigint | string) {
     super()
     if (l instanceof Literal) this.lit = l
@@ -41,24 +67,58 @@ export class ExprLit extends Expr {
     return this.lit.toString()
   }
 }
+
 export class ExprMeta extends Expr {
+  id: number
 
+  constructor (i?: number) {
+    super()
+    if (i != null) this.id = i
+    else this.id = 0
+  }
 }
+
 export class ExprFun extends Expr {
+  name: string
 
+  constructor (n: string) {
+    super()
+    this.name = n
+  }
 }
+
 export class ExprVar extends Expr {
+  var: number
 
+  constructor (v: number) {
+    super()
+    this.var = v
+  }
 }
+
 export class ExprTyped extends Expr {
+  expr: Expr
+  type: Type
 
+  constructor (e: Expr, t: Type) {
+    super()
+    this.expr = e
+    this.type = t
+  }
 }
-export class ExprImplArg extends Expr {
 
+export class ExprImplArg extends Expr {
+  expr: Expr
+
+  constructor (e: Expr) {
+    super()
+    this.expr = e
+  }
 }
 
 export class Literal {
   val: number | bigint | string
+
   constructor (v: number | bigint | string) {
     this.val = v
   }

src/runtime/javascript/ffi.ts

@@ -1,7 +1,8 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import {
   Type,
-  // Hypo,
+  Hypo,
+  Expr,
   ExprAbs,
   ExprApp,
   ExprLit,
@@ -12,8 +13,8 @@ import {
   ExprImplArg,
   Literal
 } from './expr'
+import { BE, WORDSIZE_BITS, WORDSIZE_BYTES, LINT_BASE } from './constants'
 
-import os from 'os'
 import ffi from 'ffi-napi'
 import ref, { Pointer } from 'ref-napi'
 import ref_struct from 'ref-struct-di'
@@ -47,7 +48,7 @@ export const PgfTextPtr = ref.refType(PgfText)
 
 export const PgfItorPtr = ref.refType(ref.types.void)
 
-const PgfType = ref.types.void // TODO
+const PgfType = ref.refType(ref.types.Object) // TODO
 // const PgfTypePtr = ref.refType(PgfType)
 
 const PgfTypeHypo = ref.types.void // TODO
@@ -158,18 +159,25 @@ export function PgfText_FromString (str: string): Pointer<any> {
 // 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
+  function (self, btype: boolean, name: Pointer<any>, body: Pointer<Expr>): Pointer<ExprAbs> {
+    const jsname = PgfText_AsString(name)
+    const obj = new ExprAbs(btype, jsname, body.deref())
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprAbs>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
 const eapp = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfExpr, PgfExpr],
-  function (self, fun: Pointer<any>, arg: Pointer<any>): Pointer<ExprApp> {
-    return 0 as any
+  function (self, fun: Pointer<Expr>, arg: Pointer<Type>): Pointer<ExprApp> {
+    const obj = new ExprApp(fun.deref(), arg.deref())
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprApp>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
 const elit = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfLiteral],
-  function (self, lit: Pointer<any>): Pointer<ExprLit> {
-    const litObj = lit.deref() as Literal
+  function (self, lit: Pointer<Literal>): Pointer<ExprLit> {
+    const litObj = lit.deref()
     const obj = new ExprLit(litObj)
     const buf = ref.alloc(ref.types.Object) as Pointer<ExprLit>
     ref.writeObject(buf, 0, obj)
@@ -177,35 +185,46 @@ const elit = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfLiteral],
   })
 
 const emeta = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfMetaId],
-  function (self, meta: Pointer<any>): Pointer<ExprMeta> {
-    return 0 as any
+  function (self, meta: number): Pointer<ExprMeta> {
+    const obj = new ExprMeta(meta)
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprMeta>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
 const efun = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfTextPtr],
   function (self, name: Pointer<any>): Pointer<ExprFun> {
-    return 0 as any
+    const jsname = PgfText_AsString(name)
+    const obj = new ExprFun(jsname)
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprFun>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
 const evar = ffi.Callback(PgfExpr, [PgfUnmarshaller, ref.types.int],
   function (self, index: number): Pointer<ExprVar> {
-    return 0 as any
+    const obj = new ExprVar(index)
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprVar>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
 const etyped = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfExpr, PgfType],
-  function (self, expr: Pointer<any>, type: Pointer<any>): Pointer<ExprTyped> {
-    return 0 as any
+  function (self, expr: Pointer<Expr>, type: Pointer<Type>): Pointer<ExprTyped> {
+    const obj = new ExprTyped(expr.deref(), type.deref())
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprTyped>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
 const eimplarg = ffi.Callback(PgfExpr, [PgfUnmarshaller, PgfExpr],
-  function (self, expr: Pointer<any>): Pointer<ExprImplArg> {
-    return 0 as any
+  function (self, expr: Pointer<Expr>): Pointer<ExprImplArg> {
+    const obj = new ExprImplArg(expr.deref())
+    const buf = ref.alloc(ref.types.Object) as Pointer<ExprImplArg>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
-// 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
@@ -219,7 +238,17 @@ const lint = ffi.Callback(PgfLiteral, [PgfUnmarshaller, ref.types.size_t, ref.re
         let thisval
         switch (WORDSIZE_BITS) {
           case 64:
-            thisval = BigInt((os.endianness() === 'LE') ? vals.readUInt64LE(n * WORDSIZE_BYTES) : vals.readUInt64BE(n * WORDSIZE_BYTES))
+            thisval = BigInt(BE ? vals.readUInt64BE(n * WORDSIZE_BYTES) : vals.readUInt64LE(n * WORDSIZE_BYTES))
+            break
+          case 32:
+            thisval = BigInt(BE ? vals.readUInt32BE(n * WORDSIZE_BYTES) : vals.readUInt32LE(n * WORDSIZE_BYTES))
+            break
+          case 16:
+            thisval = BigInt(BE ? vals.readUInt16BE(n * WORDSIZE_BYTES) : vals.readUInt16LE(n * WORDSIZE_BYTES))
+            break
+          case 8:
+            thisval = BigInt(vals.readUInt8(n * WORDSIZE_BYTES))
+            break
         }
         if (thisval == null) {
           throw Error(`Unsupported word size: ${WORDSIZE_BITS}`)
@@ -253,7 +282,14 @@ const lstr = ffi.Callback(PgfLiteral, [PgfUnmarshaller, PgfTextPtr],
 
 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
+    // TODO
+    const jshypos: Hypo[] = []
+    const jsname = PgfText_AsString(cat)
+    const jsexprs: Expr[] = []
+    const obj = new Type(jshypos, jsname, jsexprs)
+    const buf = ref.alloc(ref.types.Object) as Pointer<Type>
+    ref.writeObject(buf, 0, obj)
+    return buf
   })
 
 const free_ref = ffi.Callback(ref.types.void, [PgfUnmarshaller, ref.refType(ref.types.Object)],

src/runtime/javascript/index.ts

@@ -1,7 +1,20 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 
 import errno from './errno'
-import { Expr, ExprLit } from './expr'
+import {
+  Type,
+  Hypo,
+  Expr,
+  ExprAbs,
+  ExprApp,
+  ExprLit,
+  ExprMeta,
+  ExprFun,
+  ExprVar,
+  ExprTyped,
+  ExprImplArg,
+  Literal
+} from './expr'
 import {
   voidPtr,
   PgfRevisionPtr,
@@ -67,7 +80,7 @@ function handleError (err: StructObject<PgfExnType>): void {
 // ----------------------------------------------------------------------------
 // PGF grammar object
 
-export class PGFGrammar {
+class PGFGrammar {
   readonly db: Pointer<any>
   readonly revision: Pointer<any>
 
@@ -198,24 +211,72 @@ function newNGF (abstract_name: string, path?: string): PGFGrammar {
   return new PGFGrammar(db, rev)
 }
 
+function readType (str: string): Type {
+  const txt = PgfText_FromString(str)
+  const type = runtime.pgf_read_type(txt, unmarshaller.ref())
+  if (ref.isNull(type)) {
+    throw new PGFError('unable to parse type')
+  }
+  return ref.readObject(type) as Type
+}
+
 function readExpr (str: string): Expr {
   const txt = PgfText_FromString(str)
   const expr = runtime.pgf_read_expr(txt, unmarshaller.ref())
+  if (ref.isNull(expr)) {
+    throw new PGFError('unable to parse expression')
+  }
   return ref.readObject(expr) as Expr
 }
 
 // ----------------------------------------------------------------------------
 // Exposed library API
 
-export default {
+export {
+  PGFGrammar,
   PGFError,
   readPGF,
   bootNGF,
   readNGF,
   newNGF,
 
+  readType,
   readExpr,
 
+  Type,
+  Hypo,
   Expr,
-  ExprLit
+  ExprAbs,
+  ExprApp,
+  ExprLit,
+  ExprMeta,
+  ExprFun,
+  ExprVar,
+  ExprTyped,
+  ExprImplArg,
+  Literal
+}
+export default {
+  PGFGrammar,
+  PGFError,
+  readPGF,
+  bootNGF,
+  readNGF,
+  newNGF,
+
+  readType,
+  readExpr,
+
+  Type,
+  Hypo,
+  Expr,
+  ExprAbs,
+  ExprApp,
+  ExprLit,
+  ExprMeta,
+  ExprFun,
+  ExprVar,
+  ExprTyped,
+  ExprImplArg,
+  Literal
 }

src/runtime/javascript/tests/basic.test.ts

@@ -1,4 +1,19 @@
-import PGF, { PGFGrammar } from '../index'
+import PGF, {
+  PGFError,
+  PGFGrammar,
+  // Type,
+  // Hypo,
+  // Expr,
+  // ExprAbs,
+  ExprApp,
+  ExprLit,
+  ExprMeta,
+  ExprFun,
+  // ExprVar,
+  // ExprTyped,
+  ExprImplArg
+  // Literal
+} from '../index'
 import fs from 'fs'
 
 // ----------------------------------------------------------------------------
@@ -17,7 +32,7 @@ describe('readPGF', () => {
   test('GF', () => {
     expect(() => {
       PGF.readPGF('../haskell/tests/basic.gf')
-    }).toThrow(PGF.PGFError)
+    }).toThrow(PGFError)
   })
 
   test('NGF', () => {
@@ -29,7 +44,7 @@ describe('readPGF', () => {
     PGF.bootNGF('../haskell/tests/basic.pgf', './basic.ngf')
     expect(() => {
       PGF.readPGF('./basic.ngf')
-    }).toThrow(PGF.PGFError)
+    }).toThrow(PGFError)
   })
 })
 
@@ -57,13 +72,13 @@ describe('bootNGF', () => {
   test('GF', () => {
     expect(() => {
       PGF.bootNGF('../haskell/tests/basic.gf', './abc.ngf')
-    }).toThrow(PGF.PGFError)
+    }).toThrow(PGFError)
   })
 
   test('NGF', () => {
     expect(() => {
       PGF.bootNGF('./basic.ngf', './abc.ngf')
-    }).toThrow(PGF.PGFError)
+    }).toThrow(PGFError)
   })
 
   test('existing', () => {
@@ -98,13 +113,13 @@ describe('readNGF', () => {
   test('GF', () => {
     expect(() => {
       PGF.readNGF('../haskell/tests/basic.gf')
-    }).toThrow(PGF.PGFError)
+    }).toThrow(PGFError)
   })
 
   test('PGF', () => {
     expect(() => {
       PGF.readNGF('../haskell/tests/basic.pgf')
-    }).toThrow(PGF.PGFError)
+    }).toThrow(PGFError)
   })
 })
 
@@ -209,80 +224,170 @@ 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)
+describe('types', () => {
+  test('invalid', () => {
+    expect(() => {
+      PGF.readType('->')
+    }).toThrow(PGFError)
+  })
+})
+
+// ----------------------------------------------------------------------------
+
+describe('expressions', () => {
+  test('invalid', () => {
+    expect(() => {
+      PGF.readExpr('->')
+    }).toThrow(PGFError)
+  })
+
+  describe('literals', () => {
+    test('small integer', () => {
+      const e1 = PGF.readExpr('123')
+      const e2 = new ExprLit(123)
+      const e3 = new ExprLit(456)
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+
+    test('negative integer', () => {
+      const e1 = PGF.readExpr('-123')
+      const e2 = new ExprLit(-123)
+      const e3 = new ExprLit(-456)
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+
+    test('big integer', () => {
+      const e1 = PGF.readExpr('774763251095801167872')
+      const e2 = new ExprLit(BigInt('774763251095801167872'))
+      expect(e1).toEqual(e2)
+    })
+
+    test('negative big integer', () => {
+      const e1 = PGF.readExpr('-774763251095801167872')
+      const e2 = new ExprLit(BigInt('-774763251095801167872'))
+      expect(e1).toEqual(e2)
+    })
+
+    test('really big integer', () => {
+      const e1 = PGF.readExpr('7747632510958011678729003251095801167999')
+      const e2 = new ExprLit(BigInt('7747632510958011678729003251095801167999'))
+      const e3 = new 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 ExprLit(BigInt('-7747632510958011678729003251095801167999'))
+      const e3 = new ExprLit(BigInt('-7747632510958011678729003251095801167990'))
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+
+    test('float', () => {
+      const e1 = PGF.readExpr('3.142')
+      const e2 = new ExprLit(3.142)
+      const e3 = new ExprLit(2.014)
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+
+    test('negative float', () => {
+      const e1 = PGF.readExpr('-3.142')
+      const e2 = new ExprLit(-3.142)
+      const e3 = new ExprLit(-2.014)
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+
+    test('string', () => {
+      const e1 = PGF.readExpr('"abc"')
+      const e2 = new ExprLit('abc')
+      const e3 = new ExprLit('def')
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+
+    test('string unicode', () => {
+      const e1 = PGF.readExpr('"açġħ"')
+      const e2 = new ExprLit('açġħ')
+      const e3 = new ExprLit('acgh')
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+  })
+
+  describe('functions', () => {
+    test('simple', () => {
+      const e1 = PGF.readExpr('f')
+      expect(e1).toBeInstanceOf(ExprFun)
+      expect((e1 as ExprFun).name).toEqual('f')
+
+      const e2 = new ExprFun('f')
+      const e3 = new ExprFun('g')
+      expect(e1).toEqual(e2)
+      expect(e1).not.toEqual(e3)
+    })
+
+    test('application 1', () => {
+      const e1 = PGF.readExpr('f x y')
+      expect(e1).toBeInstanceOf(ExprApp)
+      expect((e1 as ExprApp).arg).toEqual(new ExprFun('y'))
+
+      const e2 = new ExprApp(
+        new ExprApp(
+          new ExprFun('f'),
+          new ExprFun('x')
+        ), new ExprFun('y')
+      )
+      expect(e1).toEqual(e2)
+    })
+
+    test('application 2', () => {
+      const e1 = PGF.readExpr('f (g x)')
+      const e2 = new ExprApp(
+        new ExprFun('f'),
+        new ExprApp(
+          new ExprFun('g'),
+          new ExprFun('x')
+        )
+      )
+      expect(e1).toEqual(e2)
+    })
+
+    test('application 3', () => {
+      const e1 = PGF.readExpr('f {g x}')
+      const e2 = new ExprApp(
+        new ExprFun('f'),
+        new ExprImplArg(
+          new ExprApp(
+            new ExprFun('g'),
+            new ExprFun('x')
+          )
+        )
+      )
+      expect(e1).toEqual(e2)
+    })
+  })
+
+  describe('variables', () => {
+    test('meta 1', () => {
+      const e1 = PGF.readExpr('?')
+      expect(e1).toBeInstanceOf(ExprMeta)
+      const e2 = new ExprMeta()
+      const e3 = new ExprMeta(0)
+      const e4 = new ExprMeta(1)
+      expect(e1).toEqual(e2)
+      expect(e1).toEqual(e3)
+      expect(e1).not.toEqual(e4)
+    })
+
+    test('meta 2', () => {
+      const e1 = PGF.readExpr('?42')
+      const e2 = new ExprMeta(42)
+      expect(e1).toEqual(e2)
+    })
   })
 })