IsLambda

IsLambda( value )
IsLambda( value )
IsLambda( value )
IsLambda( value )
is_lambda( value )
IsLambda( value )

Description

The IsLambda function returns true only if value is a Lambda function, otherwise it returns false.

Parameters

Parameter Type Definition and Requirements

value

Any

Any value, which is to be tested to determine whether it is a Lambda function or not.

Returns

Returns a Boolean, indicating whether value was a Lambda function or not.

Examples

The following query uses Map to iterate over an array of all of the types of values that can be tested by a type-check function, passing each item into a Lambda function that returns an object, which contains the value and the result of calling IsLambda with that value:

try
{
    Value result = await client.Query(
        Map(
            Arr(
                Arr("array"),
                true,
                false,
                BytesV.Of(0x1, 0x2, 0x3, 0x4),
                Arr(0x1, 0x2, 0x3, 0x4),
                Collection("Letters"),
                Ref("credentials/self"),
                Database("child_db"),
                Date("2019-11-12"),
                Ref(Collection("Letters"), 123),
                10.1,
                Function("double"),
                Index("letters"),
                10,
                Ref(Keys(), "1"),
                Query(Lambda("x", Var("x"))),
                null,
                Obj("x", 10),
                Role("employees"),
                Match(Index("letters")),
                "ten",
                "10",
                Time("2020-07-06T12:34:56.789Z"),
                Ref(Tokens(), "1")
            ),
            Lambda(
                "x",
                Obj(
                    "value", Var("x"),
                    "IsLambda", IsLambda(Var("x"))
                )
            )
        )
    );

    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}
Arr(ObjectV(value: Arr(StringV(array)),IsLambda: BooleanV(False)), ObjectV(value: BooleanV(True),IsLambda: BooleanV(False)), ObjectV(value: BooleanV(False),IsLambda: BooleanV(False)), ObjectV(value: BytesV(0x01, 0x02, 0x03, 0x04),IsLambda: BooleanV(False)), ObjectV(value: Arr(LongV(1), LongV(2), LongV(3), LongV(4)),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "Letters", collection = RefV(id = "collections")),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "295432834428961280", collection = RefV(id = "credentials")),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "child_db", collection = RefV(id = "databases")),IsLambda: BooleanV(False)), ObjectV(value: FaunaDate(2019-11-12 12:00:00 AM),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "123", collection = RefV(id = "Letters", collection = RefV(id = "collections"))),IsLambda: BooleanV(False)), ObjectV(value: DoubleV(10.1),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "double", collection = RefV(id = "functions")),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "letters", collection = RefV(id = "indexes")),IsLambda: BooleanV(False)), ObjectV(value: LongV(10),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "1", collection = RefV(id = "keys")),IsLambda: BooleanV(False)), ObjectV(value: QueryV(System.Collections.Generic.Dictionary`2[System.String,FaunaDB.Query.Expr]),IsLambda: BooleanV(True)), ObjectV(value: NullV,IsLambda: BooleanV(False)), ObjectV(value: ObjectV(x: LongV(10)),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "employees", collection = RefV(id = "roles")),IsLambda: BooleanV(False)), ObjectV(value: SetRefV(System.Collections.Generic.Dictionary`2[System.String,FaunaDB.Types.Value]),IsLambda: BooleanV(False)), ObjectV(value: StringV(ten),IsLambda: BooleanV(False)), ObjectV(value: StringV(10),IsLambda: BooleanV(False)), ObjectV(value: FaunaTime(2020-07-06T12:34:56.789Z),IsLambda: BooleanV(False)), ObjectV(value: RefV(id = "1", collection = RefV(id = "tokens")),IsLambda: BooleanV(False)))
result, err := client.Query(
	f.Map(
		f.Arr{
			f.Arr{"array"},
			true,
			false,
			f.BytesV{0x01, 0x02, 0x03, 0x04},
			f.Arr{0x1, 0x2, 0x3, 0x4},
			f.Collection("Letters"),
			f.Ref("credentials/self"),
			f.Database("child_db"),
			f.Date("2019-11-12"),
			f.Ref(f.Collection("Letters"), 123),
			10.1,
			f.Function("double"),
			f.Index("letters"),
			10,
			f.Ref(f.Keys(), "1"),
			f.Query(f.Lambda("x", f.Var("x"))),
			nil,
			f.Null(),
			f.Obj{"x": 10},
			f.Role("employees"),
			f.Match(f.Index("letters")),
			"ten",
			"10",
			f.Time("2020-07-06T12:34:56.789Z"),
			f.Ref(f.Tokens(), "1"),
		},
		f.Lambda("x", f.Obj{
			"value": f.Var("x"),
			"IsLambda": f.IsLambda(f.Var("x")),
		})))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}
[map[IsLambda:false value:[array]] map[IsLambda:false value:true] map[IsLambda:false value:false] map[IsLambda:false value:[1 2 3 4]] map[IsLambda:false value:[1 2 3 4]] map[IsLambda:false value:{Letters 0xc0001701e0 0xc0001701e0 <nil>}] map[IsLambda:false value:{280481857410171392 0xc000170300 0xc000170300 <nil>}] map[IsLambda:false value:{child_db 0xc000170420 0xc000170420 <nil>}] map[IsLambda:false value:{0 63709113600 <nil>}] map[IsLambda:false value:{123 0xc000194150 0xc000194150 <nil>}] map[IsLambda:false value:10.1] map[IsLambda:false value:{double 0xc0001942a0 0xc0001942a0 <nil>}] map[IsLambda:false value:{letters 0xc0001943c0 0xc0001943c0 <nil>}] map[IsLambda:false value:10] map[IsLambda:false value:{1 0xc000194510 0xc000194510 <nil>}] map[IsLambda:true value:{[123 34 97 112 105 95 118 101 114 115 105 111 110 34 58 34 51 34 44 34 108 97 109 98 100 97 34 58 34 120 34 44 34 101 120 112 114 34 58 123 34 118 97 114 34 58 34 120 34 125 125]}] map[IsLambda:false value:{}] map[IsLambda:false value:{}] map[IsLambda:false value:map[x:10]] map[IsLambda:false value:{employees 0xc000194720 0xc000194720 <nil>}] map[IsLambda:false value:{map[match:{letters 0xc000194870 0xc000194870 <nil>}]}] map[IsLambda:false value:ten] map[IsLambda:false value:10] map[IsLambda:false value:{789000000 63729635696 <nil>}] map[IsLambda:false value:{1 0xc000194a20 0xc000194a20 <nil>}]]
System.out.println(
    client.query(
        Map(
            Arr(
                Arr(Value("array")),
                Value(true),
                Value(false),
                Value(new byte[] {0x1, 0x2, 0x3, 0x4}),
                Arr(Value(0x1), Value(0x2), Value(0x3), Value(0x4)),
                Collection("Letters"),
                Ref("credentials/self"),
                Database("child_db"),
                Date("2019-11-12"),
                Ref(Collection("Letters"), "123"),
                Value(10.1),
                Function("double"),
                Index("letters"),
                Value(10),
                Ref(Keys(), "1"),
                Query(Lambda("x", Var("x"))),
                Null(),
                Obj("x", Value(10)),
                Role("employees"),
                Match(Index("letters")),
                Value("ten"),
                Value("10"),
                Time("2020-07-06T12:34:56.789Z"),
                Ref(Tokens(), "1")
            ),
            Lambda(
                "x",
                Obj("value", Var("x"), "IsLambda", IsLambda(Var("x")))
            )
        )
    ).get());
[{value: ["array"], IsLambda: false}, {value: true, IsLambda: false}, {value: false, IsLambda: false}, {value: [0x01 0x02 0x03 0x04], IsLambda: false}, {value: [1, 2, 3, 4], IsLambda: false}, {value: ref(id = "Letters", collection = ref(id = "collections")), IsLambda: false}, {value: ref(id = "286816445084467712", collection = ref(id = "credentials")), IsLambda: false}, {value: ref(id = "child_db", collection = ref(id = "databases")), IsLambda: false}, {value: 2019-11-12, IsLambda: false}, {value: ref(id = "123", collection = ref(id = "Letters", collection = ref(id = "collections"))), IsLambda: false}, {value: 10.1, IsLambda: false}, {value: ref(id = "double", collection = ref(id = "functions")), IsLambda: false}, {value: ref(id = "letters", collection = ref(id = "indexes")), IsLambda: false}, {value: 10, IsLambda: false}, {value: ref(id = "1", collection = ref(id = "keys")), IsLambda: false}, {value: QueryV({api_version=4, lambda=x, expr={var=x}}), IsLambda: true}, {value: null, IsLambda: false}, {value: {x: 10}, IsLambda: false}, {value: ref(id = "employees", collection = ref(id = "roles")), IsLambda: false}, {value: {@set = {match: ref(id = "letters", collection = ref(id = "indexes"))}}, IsLambda: false}, {value: "ten", IsLambda: false}, {value: "10", IsLambda: false}, {value: 2020-07-06T12:34:56.789Z, IsLambda: false}, {value: ref(id = "1", collection = ref(id = "tokens")), IsLambda: false}]
client.query(
  q.Map(
    [
      ['array'],
      true,
      false,
      new Uint8Array([1, 2, 3, 4]),
      [0x1, 0x2, 0x3, 0x4],
      q.Collection('Letters'),
      q.Ref('credentials/self'),
      q.Database('child_db'),
      q.Date('2019-11-12'),
      q.Ref(q.Collection('Letters'), 123),
      10.1,
      q.Function('double'),
      q.Index('letters'),
      10,
      q.Ref(q.Keys(), '1'),
      q.Query(q.Lambda('x', q.Var('x'))),
      null,
      { x: 10 },
      q.Role('employees'),
      q.Match(q.Index('letters')),
      'ten',
      '10',
      q.Time('2020-07-06T12:34:56.789Z'),
      q.Ref(q.Tokens(), '1'),
    ],
    q.Lambda('x', {
      value: q.Var('x'),
      IsLambda: q.IsLambda(q.Var('x')),
    })
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))
[
  { value: [ 'array' ], IsLambda: false },
  { value: true, IsLambda: false },
  { value: false, IsLambda: false },
  { value: Bytes("AQIDBA=="), IsLambda: false },
  { value: [ 1, 2, 3, 4 ], IsLambda: false },
  { value: Collection("Letters"), IsLambda: false },
  { value: Ref(Credentials(), "268432682046718464"), IsLambda: false },
  { value: Database("child_db"), IsLambda: false },
  { value: Date("2019-11-12"), IsLambda: false },
  { value: Ref(Collection("Letters"), "123"), IsLambda: false },
  { value: 10.1, IsLambda: false },
  { value: Function("double"), IsLambda: false },
  { value: Index("letters"), IsLambda: false },
  { value: 10, IsLambda: false },
  { value: Ref(Keys(), "1"), IsLambda: false },
  { value: Query(Lambda("x", Var("x"))), IsLambda: true },
  { value: null, IsLambda: false },
  { value: { x: 10 }, IsLambda: false },
  { value: Role("employees"), IsLambda: false },
  { value: Match(Index("letters")), IsLambda: false },
  { value: 'ten', IsLambda: false },
  { value: '10', IsLambda: false },
  { value: Time("2020-06-15T21:23:25.676Z"), IsLambda: false },
  { value: Ref(Tokens(), "1"), IsLambda: false }
]
result = client.query(
  q.map_(
    q.lambda_("x", {
      "value": q.var("x"),
      "IsLambda": q.is_lambda(q.var("x")),
    }),
    [
      ["array"],
      True,
      False,
      bytearray([1, 2, 3, 4]),
      [0x1, 0x2, 0x3, 0x4],
      q.collection("Letters"),
      q.ref("credentials/self"),
      q.database("child_db"),
      q.date("2019-11-12"),
      q.ref(q.collection("Letters"), 123),
      10.1,
      q.function("double"),
      q.index("letters"),
      10,
      q.ref(q.keys(), "1"),
      q.query(q.lambda_("x", q.var("x"))),
      None,
      {"x": 10},
      q.role("employees"),
      q.match(q.index("letters")),
      "ten",
      "10",
      q.time("2020-07-06T12:34:56.789Z"),
      q.ref(q.tokens(), "1"),
    ],
  )
)
print(result)
[{'value': ['array'], 'IsLambda': False}, {'value': True, 'IsLambda': False}, {'value': False, 'IsLambda': False}, {'value': bytearray(b'\x01\x02\x03\x04'), 'IsLambda': False}, {'value': [1, 2, 3, 4], 'IsLambda': False}, {'value': Ref(id=Letters, collection=Ref(id=collections)), 'IsLambda': False}, {'value': Ref(id=282032258185953792, collection=Ref(id=credentials)), 'IsLambda': False}, {'value': Ref(id=child_db, collection=Ref(id=databases)), 'IsLambda': False}, {'value': datetime.date(2019, 11, 12), 'IsLambda': False}, {'value': Ref(id=123, collection=Ref(id=Letters, collection=Ref(id=collections))), 'IsLambda': False}, {'value': 10.1, 'IsLambda': False}, {'value': Ref(id=double, collection=Ref(id=functions)), 'IsLambda': False}, {'value': Ref(id=letters, collection=Ref(id=indexes)), 'IsLambda': False}, {'value': 10, 'IsLambda': False}, {'value': Ref(id=1, collection=Ref(id=keys)), 'IsLambda': False}, {'value': Query({'api_version': '4', 'lambda': 'x', 'expr': {'var': 'x'}}), 'IsLambda': True}, {'value': None, 'IsLambda': False}, {'value': {'x': 10}, 'IsLambda': False}, {'value': Ref(id=employees, collection=Ref(id=roles)), 'IsLambda': False}, {'value': SetRef({'match': Ref(id=letters, collection=Ref(id=indexes))}), 'IsLambda': False}, {'value': 'ten', 'IsLambda': False}, {'value': '10', 'IsLambda': False}, {'value': FaunaTime('2020-07-06T12:34:56.789Z'), 'IsLambda': False}, {'value': Ref(id=1, collection=Ref(id=tokens)), 'IsLambda': False}]
Map(
  [
    ['array'],
    true,
    false,
    new Uint8Array([1, 2, 3, 4]),
    [0x1, 0x2, 0x3, 0x4],
    Collection('Letters'),
    Ref('credentials/self'),
    Database('child_db'),
    Date('2019-11-12'),
    Ref(Collection('Letters'), 123),
    10.1,
    Function('double'),
    Index('letters'),
    10,
    Ref(Keys(), '1'),
    Query(Lambda('x', Var('x'))),
    null,
    { x: 10 },
    Role('employees'),
    Match(Index('letters')),
    'ten',
    '10',
    Time('2020-07-06T12:34:56.789Z'),
    Ref(Tokens(), '1'),
  ],
  Lambda('x', {
    value: Var('x'),
    IsLambda: IsLambda(Var('x')),
  })
)
[
  { value: [ 'array' ], IsLambda: false },
  { value: true, IsLambda: false },
  { value: false, IsLambda: false },
  { value: { '0': 1, '1': 2, '2': 3, '3': 4 }, IsLambda: false },
  { value: [ 1, 2, 3, 4 ], IsLambda: false },
  { value: Collection("Letters"), IsLambda: false },
  { value: Ref(Credentials(), "302043979982045696"), IsLambda: false },
  { value: Database("child_db"), IsLambda: false },
  { value: Date("2019-11-12"), IsLambda: false },
  { value: Ref(Collection("Letters"), "123"), IsLambda: false },
  { value: 10.1, IsLambda: false },
  { value: Function("double"), IsLambda: false },
  { value: Index("letters"), IsLambda: false },
  { value: 10, IsLambda: false },
  { value: Ref(Keys(), "1"), IsLambda: false },
  { value: Query(Lambda("x", Var("x"))), IsLambda: true },
  { value: null, IsLambda: false },
  { value: { x: 10 }, IsLambda: false },
  { value: Role("employees"), IsLambda: false },
  { value: Match(Index("letters")), IsLambda: false },
  { value: 'ten', IsLambda: false },
  { value: '10', IsLambda: false },
  { value: Time("2020-07-06T12:34:56.789Z"), IsLambda: false },
  { value: Ref(Tokens(), "1"), IsLambda: false }
]
Query metrics:

  •    bytesIn:   600

  •   bytesOut: 1,583

  • computeOps:     2

  •    readOps:     0

  •   writeOps:     0

  •  readBytes:   373

  • writeBytes:     0

  •  queryTime:  21ms

  •    retries:     0

This query operates on a pre-existing schema, which is not provided here.

Also, the query is executed via a client connection, that uses a secret acquired by calling the Login function (not shown here), so that Ref("credentials/self") returns a valid value.

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