Using the functions

Cascade Expressions: cascade call

Cascade Expressions

There are some places where you may use either literal value or cascade expression. These places are:

parameter's output cell,
parameter's input cell,
domain attribute value,
input level's property (source value).

There are 2 types of cascade expressions:

cascade get - redirects evaluation to given parameter,
cascade call - redirects evaluation to given function.

Basic information about cascade call:

every cascade call starts with $f symbol, which means cascade to function,
when cascading to function, you may pass arguments to that function,
when cascading to function, you may extract value from compound result.

Below you can see 3 basic usages of cascade expressions:

1) Cascade expression inside parameter's output cell:

2) Cascade expression used in domain attribute:

3) Cascade expression used in level source:

Cascade call

Everywhere you use Cascade call expression it redirects evaluation to given function and takes value that function returns.

Cascade call syntax:

cascade statement

meaning

$f fun

evaluates function fun and takes its result

$f fun (1, 5, active)

function is called with 3 arguments passed: "1", "5" and "active",note that arguments are always passed as string values

$f fun (1; 5; A,B,C)

if semicolon ; is present anywhere in arguments expression - Hyperon will use that semicolon as argument delimiter, otherwise it will use comma , as delimiter,
note that this call will pass 3 string arguments: "1", "5", "A,B,C"

$f fun (ctx:insured.age, 5)

you may pass values taken directly from current context by using ctx:path syntax,
note that this example will take first argument from current context
with standard context API: ctx.get( "insured.age" )

$f fun [ idx ]

if function returns compound result (ParamValue, MultiValue, java array, Collection or Iterable), then cascade call extracts element from position idx, where idx = 0 is first element

$f fun [ code ]

if function returns compound result (ParamValue, MultiValue or Map),
then cascade call extracts element associated with key = code - result.get(code)

$f fun (1, ctx:prd.code) [factor]

one more example: fun is called with 2 arguments, first is given as a literal,
second is taken from current context from prd.code path, and finally - Hyperon extracts "factor" field from function's compound result.

Implicit type conversion

Suppose, you have parameter P with level L1 of type T1, and function F returning value of type T2. If you use cascade call inside P[L1] pointing to F, then:

step 1: internally cascade call will return value of type T2, internally cascade
step 2: next, T2 will be converted to Holder,

conversion will meet Hyperon's conversion standards, see _dec(), _num(), _str(), _date(), _bool() conversion methods,
conversion may be lossy (eg. T1 is integer while T2 is number)

Example

Suppose we have function calc.factors and parameter client.factors defined as follows:

Function calc.factors:

function (age) {

    // normalize arguments (this is recommended as they may come as strings)
    age = _num( age );

    var factor1 = 1.0 + age/100;
    var factor2 = 3.0 + age/10;

    // return f1 mapped to factor1, and f2 mapped to factor2
    return util.map(
        'f1', factor1,
        'f2', factor2
    );
}

Parameter client.factors:

IN
insured.age

OUT
factor1 (integer)

OUT
factor2 (number)

0 - 30

1.0

3.0

31 - 40

1.1

$f calc.factors (ctx:insured.age) [f2]

41 - 50

1.2

$f calc.factors (50) [f2]

$f calc.factors (65) [f1]

$f calc.factors (50) [f2]

Below you can see parameter's results for some values of insured.age property:

insured.age

factor1

factor2

1.0

3.0

1.1

6.7

1.2

8.0

1.65

9.5

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Using the functions

Function Logging Levels

Cascade Expressions: cascade call

Hyperon util methods