Lambda

The following query uses the Map function to provide a single argument to the Lambda. The Lambda takes the parameter called name, resolves it to the value "Hen ", and then provides it to the first parameter to concatenate with the string "Wen". The result of "Hen Wen" is then returned.

client.query(
  q.Map(
    ['Hen '],
    q.Lambda(
      'name',
      q.Concat([q.Var('name'), 'Wen']),
    ),
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))

[ 'Hen Wen' ]

result = client.query(
  q.map_(
    q.lambda_(
      "name",
      q.concat([q.var("name"), "Wen"])
    ),
    ["Hen "]
  )
)
print(result)

[ "Hen Wen" ]

result, err := client.Query(
	f.Map(
		f.Arr{"Hen "},
		f.Lambda(
			"name",
			f.Concat(f.Arr{f.Var("name"), "Wen"}),
		),
	))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}

[Hen Wen]

try
{
    Value result = await client.Query(
        Map(
            Arr("Hen "),
            Lambda(
                "name",
                Concat(Arr(Var("name"), "Wen"))
            )
        )
    );
    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}

Arr(StringV(Hen Wen))

System.out.println(
    client.query(
        Map(
            Arr(Value("Hen ")),
            Lambda(
                Value("name"),
                Concat(Arr(Var("name"), Value("Wen")))
            )
        )
    ).get());

["Hen Wen"]

Map(
  ['Hen '],
  Lambda(
    "name",
    Concat([Var("name"), "Wen"])
  ),
)

[ 'Hen Wen' ]

The following query passes multiple arguments to a Lambda. The number of values in the array passed into the Lambda and the number of arguments in the Lambda must match exactly. In this example, the Map passes an array with two elements and the Lambda takes an array with two elements. The Lambda resolves the two arguments to their values and then calls the Concat function with the values.

client.query(
  q.Map(
    [['Hen', 'Wen']],
    q.Lambda(
      ['f', 'l'],
      q.Concat([q.Var('f'), q.Var('l')], ' ')
    ),
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))

[ 'Hen Wen' ]

result = client.query(
  q.map_(
    lambda f, l: q.concat([f, l], " "),
    [["Hen", "Wen"]]
  )
)
print(result)

[ "Hen Wen" ]

result, err := client.Query(
	f.Map(
		f.Arr{f.Arr{"Hen", "Wen"}},
		f.Lambda(
			f.Arr{"f", "l"},
			f.Concat(
				f.Arr{
					f.Var("f"), f.Var("l"),
				},
				f.Separator(" "),
			))))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}

[Hen Wen]

try
{
    Value result = await client.Query(
        Map(
            Arr(Arr("Hen", "Wen")),
            Lambda(Arr("f", "l"), Concat(Arr(Var("f"), Var("l")), " "))
        )
    );
    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}

Arr(StringV(Hen Wen))

System.out.println(
    client.query(
        Map(
            Arr(
                Arr(Value("Hen"), Value("Wen"))
            ),
            Lambda(
                Arr(Value("f"),Value("l")),
                Concat(Arr(Var("f"), Var("l")), Value(" "))
            )
        )
    ).get());

["Hen Wen"]

Map(
  [['Hen', 'Wen']],
  Lambda(
    ['f', 'l'],
    Concat([Var('f'), Var('l')], ' ')
  ),
)

[ 'Hen Wen' ]

The following query passes more arguments to the Lambda than are declared. In this case, the _ (underscore) has been provided to the params array so that the Lambda function knows to discard the extra arguments. If the _ had not been provided, this function would have returned an error.

client.query(
  q.Map(
    [['Hen', 'Wen']],
    q.Lambda(['f', '_'], q.Var('f')),
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))

[ 'Hen' ]

result = client.query(
  q.map_(
    q.lambda_(["f", "_"], q.var("f")),
    [["Hen", "Wen"]]
  )
)
print(result)

[ "Hen" ]

result, err :=	client.Query(
	f.Map(
		f.Arr{f.Arr{"Hen", "Wen"}},
		f.Lambda(f.Arr{"f", "_"}, f.Var("f"))))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}

[Hen]

try
{
    Value result = await client.Query(
        Map(
            Arr(Arr("Hen", "Wen")),
            Lambda(Arr("f", "_"), Var("f"))
        )
    );
    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}

Arr(StringV(Hen))

System.out.println(
    client.query(
        Map(
            Arr(Arr(Value("Hen"), Value("Wen"))),
            Lambda(
                Arr(Value("f"),Value("_")),
                Concat(Arr(Var("f")), Value(" "))
            )
        )
    ).get());

["Hen"]

Map(
  [['Hen', 'Wen']],
  Lambda(['f', '_'], Var('f')),
)

[ 'Hen' ]

The following query uses the Map function to provide two objects to the Lambda as the user parameter. The Lambda selects the email field from each object, which becomes part of the response:

client.query(
  q.Map(
    [
      {
        name: 'Hen Wen',
        email: 'henwen@black.cauldron',
      },
      {
        name: 'Taran',
        email: 'taran@black.cauldron',
      },
    ],
    q.Lambda(
      'user',
      q.Select(['email'], q.Var('user'))
    )
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))

[ 'henwen@black.cauldron', 'taran@black.cauldron' ]

result = client.query(
  q.map_(
    q.lambda_(
      "user",
      q.select(["email"], q.var("user"))
    ),
    [
      {
        "name": "Hen Wen",
        "email": "henwen@black.cauldron"
      },
      {
        "name": "Taran",
        "email": "taran@black.cauldron"
      }
    ]
  )
)
print(result)

['henwen@black.cauldron', 'taran@black.cauldron']

result, err := client.Query(
	f.Map(
		f.Arr{
			f.Obj{
				"name": "Hen Wen",
				"email": "henwen@black.cauldron",
			},
			f.Obj{
				"name": "Taran",
				"email": "taran@black.cauldron",
			},
		},
		f.Lambda(
			"user",
			f.Select(f.Arr{"email"}, f.Var("user")),
		),
	))


if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}

[henwen@black.cauldron taran@black.cauldron]

try
{
    Value result = await client.Query(
        Map(
            Arr(
                Obj(
                    "name", "Hen Wen",
                    "email", "henwen@black.cauldron"
                ),
                Obj(
                    "name", "Taran",
                    "email", "taran@black.cauldron"
                )
            ),
            Lambda(
                "user",
                Select(Arr("email"), Var("user"))
            )
        )
    );
    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}

Arr(StringV(henwen@black.cauldron), StringV(taran@black.cauldron))

System.out.println(
    client.query(
        Map(
            Arr(
                Obj(
                    "name", Value("Hen Wen"),
                    "email", Value("henwen@black.cauldron")
                ),
                Obj(
                    "name", Value("Taran"),
                    "email", Value("taran@black.cauldron")
                )
            ),
            Lambda(
                "user",
                Select(Arr(Value("email")), Var("user"))
            )
        )

    ).get());

["henwen@black.cauldron", "taran@black.cauldron"]

Map(
  [
    {
      name: 'Hen Wen',
      email: 'henwen@black.cauldron',
    },
    {
      name: 'Taran',
      email: 'taran@black.cauldron',
    },
  ],
  Lambda(
    'user',
    Select(['email'], Var('user'))
  )
)

[ 'henwen@black.cauldron', 'taran@black.cauldron' ]