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Functions and Expressions
Use HCL Link functions and expressions to create component rules and map rules.
Expressions and evaluations
The documentation provided here describes HCL Link functions and expressions. Functions and expressions are used to create component rules and map rules.
Map names in expressions
Map names in expressions that are used in map rules represent calls to functional maps.
Evaluation of functional maps in an expression
A single evaluation of a functional map requires one object for each input argument. The result of the evaluation is always one output object.

Functions and Expressions
Use HCL Link functions and expressions to create component rules and map rules.
- Expressions and evaluations
  The documentation provided here describes HCL Link functions and expressions. Functions and expressions are used to create component rules and map rules.
  - Expressions
    An expression is a statement about data objects. Expressions are used in component rules in the schema designer and in map rules in the map designer.
  - Literals
    A literal is a constant value. A literal may be a number or a text string.
  - Data object names
    A data object is referenced in an expression by its name.
  - Evaluating expressions
    Expressions are evaluated based on the context in which data object names, literals, operators, function names and map names appear in the expression, and the data on which it operates. .
  - Operators
    Operators are used for arithmetic functions and text functions on items.
  - Using functions in expressions
    Functions perform a particular action on its input arguments.
  - Map names in expressions
    Map names in expressions that are used in map rules represent calls to functional maps.
    - Evaluation of functional maps in an expression
      A single evaluation of a functional map requires one object for each input argument. The result of the evaluation is always one output object.
  - Expressions that evaluate to NONE
    The following discussion explains how the map designer evaluates an expression when expressions within it evaluate to "none".
  - Evaluated expressions assigned to output items
    When an output item is defined, then it is determined from the result of the evaluated expression.
  - Automatic item format conversions
    When an item is assigned an output value, the map designer will automatically convert an item with the same interpretation (either number, text, date, or time) from one presentation to another.
- Using functions
  A function is an expression that generates an output by performing a certain operation on one or more inputs.
- Syntax of a function
  The following is an example of a function:
- Function argument syntax
  Arguments typically have some restrictions on the expression used for that argument.
- Character-set encoding functions
  Functions that use the HCL Link EXIT architecture convert data to the native character set of the platform as part of the function call.
- General functions
  There are several general functions you can call from map rule to process input.
- Bidirectional functions
  Bidirectional languages such as Arabic and Hebrew are languages in which the text is presented to the user ordered from right to left, but numbers and Latin alphabetic strings within the text are presented left to right.
- Bit manipulation and testing functions
  You can use this function to manipulate and to test a bit in a binary number.
- Cache functions
  Use cache functions to specify a value for each of the cache variables defined for a flow, and additionally, to alter an already specified value for a cache variable.
- Conversion functions
  You can use this function to convert an expression from one datatype to another datatype.
- Date/time functions
  You can use this function to perform various operations on date and time.
- Error handling functions
  You can use this function in evaluating the type of error during map execution.
- External interface functions
  You can use this function to retrieve data from a database from within in a map rule.
- Flow functions
  Use Flow functions to specify a value for each of the flow variables defined for a flow, and additionally, to alter an already specified value for a flow variable.
- Inspection functions
  You can use this function to test and inspect the object.
- Logical functions
  Logical functions provide a way to use logical conditions to display one of several values.
- Lookup and reference functions
  These function search operates by scanning the appropriate set of items in sequence, attempting to match the logical condition.
- Math and statistics functions
  Precede all MATHLIB functions with mathlib->
- Text functions
  These functions are used to convert the text item in a map rule.
- XML functions
  There are several XML functions that you can call from component rules and map rules to process input XML data.
- Custom functions
  From the Type Designer or Map Designer, you can create custom functions to call external libraries.
- Date and time format strings
  You can use the listed format strings for numbers, dates and times in functions such as the CURRENTDATETIME, FROMNUMBER, TONUMBER, FROMDATETIME, and TODATETIME.
- Number format strings
  You can create custom number formats by using the given format strings.
- RUN function return codes
  The RUN function return codes and messages might result when using the RUN function.
- Character set codes for CPACKAGE, CSERIESTOTEXT, and CTEXT
  The second argument of the CPACKAGE, CSERIESTOTEXT, and CTEXT functions specifies the character set of the output of the function. The value of the second argument (the character set of the object content), must be a valid character set code.

Evaluation of functional maps in an expression

A single evaluation of a functional map requires one object for each input argument. The result of the evaluation is always one output object.

As with functions and operators, when a functional map is used in an expression, evaluation sets for that expression might cause the functional map to be evaluated many times.

Consider the following expression:

MakeForm ( EntryForm:Input , GroupInfo:Input )

If there are two occurrences of GroupInfo and four occurrences of EntryForm, the map MakeForm will be evaluated once per combination of EntryForm and GroupInfo-a total of (2 x 4) = 8 times.

Consider another expression:

Fmap ( a:Input , b:Input , c:Input )

The objects a, b, and c have only Input in common. The expression that contains the Fmap reference will be evaluated once per combination of a, b, and c.

To illustrate how the functional map will be evaluated, use a very simple data file of a's, b's, and c's. Each time the map is evaluated, one a object, one b object, and one c object are selected. The first time the map is evaluated, the data objects are a1, b1, and c1. The next time it is evaluated, the data objects are a2, b1, and c1, and so on.

An important difference in how the map designer evaluates a functional map in an expression is when an input argument evaluates to none.

See When an Input Argument of a Function Evaluates to NONE.