Export Directives

Export directives are used to write computation results to files.

Syntax

The syntax of an export directive is as follows:

@export <predicate> :- <format>{<parameter>=<value>, ...} .

For example, the following export writes a CSV file that contains two columns, with the first formatted as plain string and the second as an integer. The third parameter of the exported predicate result is skipped and will not be in the file:

@export result :- csv{resource="out.csv.gz", format=(string,int,skip)} .

The output will be gzipped (guessed from file name). Tuples that contain anything other than a string in the first component and an integer in the second will not be exported and ignored silently.

Formats

Currently the following formats are supported:

Format	Parameters
csv	Comma-separated values.
dsv	Delimited separated values. (Like csv, but allows specifying different delimiters e.g. delimiter=";")
tsv	Tab-separated values.
rdf	Generic RDF format. The actual format will be guessed using the file name.
nquads	RDF NQuads format.
trig	RDF TriG format.
ntriples	RDF Ntriples format
rdfxml	RDF/XML format.
turtle	RDF Turtle format.

Available parameters

csv

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

ignore_headers if true, the first record (containing the column headers) is ignored Accepted type(s): Boolean

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

dsv

delimiter The delimiter to use. Accepted type(s): Character

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

ignore_headers if true, the first record (containing the column headers) is ignored Accepted type(s): Boolean

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

tsv

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

ignore_headers if true, the first record (containing the column headers) is ignored Accepted type(s): Boolean

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

rdf

base Specify the base IRI to be used when importing RDF data; if given, relative IRIs will be made absolute based on this base; otherwise, relative IRIs remain relative in Nemo Accepted type(s): String

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

nquads

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

base Specify the base IRI to be used when importing RDF data; if given, relative IRIs will be made absolute based on this base; otherwise, relative IRIs remain relative in Nemo Accepted type(s): String

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

trig

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

base Specify the base IRI to be used when importing RDF data; if given, relative IRIs will be made absolute based on this base; otherwise, relative IRIs remain relative in Nemo Accepted type(s): String

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

ntriples

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

base Specify the base IRI to be used when importing RDF data; if given, relative IRIs will be made absolute based on this base; otherwise, relative IRIs remain relative in Nemo Accepted type(s): String

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

rdfxml

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

base Specify the base IRI to be used when importing RDF data; if given, relative IRIs will be made absolute based on this base; otherwise, relative IRIs remain relative in Nemo Accepted type(s): String

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

turtle

resource The file name to write to. If it contains an extension, this is used to automatically set the compression parameter. If set to the empty string "", the tuples are read from stdin. This is restricted to one stdin resource per program. If omitted, this is set based on the predicate name, file format and compression type <predicate-name>.<format>.<compression>. Accepted type(s): IRI, String

format The input-format of the imported data. Might be int, double, string, rdf or skip. Accepted type(s): Tuple of Nemo type names, Nemo type name

compression The compression to use. Currently only gzip or none is supported. ' This will normally be guessed correctly from the file extension, but can be useful for non-standard file names or URLs. Accepted type(s): String

limit The maximum number of tuples to import. (great for testing when working with large files) Accepted type(s): Unsigned integer

base Specify the base IRI to be used when importing RDF data; if given, relative IRIs will be made absolute based on this base; otherwise, relative IRIs remain relative in Nemo Accepted type(s): String

http_headers Each pair is added as HTTP headers when making an HTTP request Accepted type(s): Map with key-value pairs that can be of type: String, Constant or Number Example: http_headers=("Accept-Language"="en-US","Accept-Charset="utf-8")

http_get_parameters The map will be flattened into pairs that are appended to the IRI before making an HTTP request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_get_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

http_post_parameters The map will be flattened into pairs that are sent as the body of an HTTP POST request Accepted type(s): Map where each key is of type String, Constant or Number and each value is a (possibly unary) tuple containing Strings, Numbers and Constants. Example: http_post_parameters={name="John Doe", age=42, parent=("Johanna Doe", "Josh Doe")}

iri_fragment A fragment that is appended to a resource or endpoint IRI Accepted type(s): String

sparql

json

When using the Nemo command-line client, some cli options are available to override the export directives in the program, to set the output (base) directory, and to control if existing files should be overwritten.

The parameters in export directives can also make use of format strings, e.g.,

@export table :- csv{resource = f"file-{?x}-{?y}.csv"}, ?x = "name", ?y = 42 .