Syntax and types
- Jonathan Muse
- Shane Smith
To use SIL like any other scripting language follow a few simple syntax rules.
General rules
All instructions end with a semicolon ;
Comments are introduced using //comment_until_end_of_line or /* comment */
Example
// single line comment
/*
this comment
spans over
multiple lines
*/ Types
Basic Types
SIL defines the following base types:
string - defines a string, example literal is "abc"
boolean - defines boolean values true and false
number - any numeric value
integer - a numeric value without a fractional component
byte - a byte
date - a date, like "2010-03-30"
interval - a time interval, like "2d 3h"
Important notes
interval - data type does not represent the working interval (i.e. 8h), but the full interval. When we created SIL™ we thought about if we should introduce a working interval type (i.e. 8h / day) but this would have certain undesired implications (how long is your workday? in France, for instance, Friday is only 6h). With our custom fields, it's a matter of interpretation of the interval, and we have functions to help you transform a 24h interval to a working interval, or you can simply write your own.
date - data type can be used to represent dates and date-times.
number - data type internal storage is represented only by real numbers (double). However, the language accepts for historical reasons type declarations as "real", "double", "float" (treating them as "number", of course).
integer (or int) - is actually a long in the traditional sense
Arrays
Multi-value (arrays) types are also supported and composed of the base type followed by the array symbols [ ] for each dimension of the array type. This translates to the following being valid array types:
string[]
boolean[]
number[][]
integer[]
date[][][]
interval[]
Person[][] - where Person is a user-defined structure
Key-Value Arrays (Maps)
Arrays are actually maps where values are keyed by their position in the list, and so key-value arrays are declared the same as regular arrays.
Learn more about maps and the indexing operator.
Structures
The general syntax for defining a structure is:
struct <name> {
<type> <fieldName>;
}Structures are defined by their name and pairs of field type and field name. A structure can have any number of fields. The type of each field can be a simple type, a user-defined structure (including the structure being defined) or arrays of these types.
Example:
struct Person {
string id;
string name;
date birthDate;
Person manager;
Person [] subordinates;
}To access the value of a field from a variable the syntax will look like:
Initializing Structures:
Example 1
Example 2
Literals
This topic is about constant values, NOT about the read-only attribute of variables.
Single Value Literals
For numbers, integers and boolean values, constants are represented without any additional alterations.
Example
Literals for string, date and interval are provided between double quotes (").
The full format for date is "yyyy-MM-ddTHH:mm:ss.SSSZ", and may include the time-zone information at the end. The short format "yyyy-MM-dd" is accepted as well.
The intervals should be provided in the JIRA standard format: "1w 2d 3h 4m".
Example
Array Literals
Array literals are created using the following syntax:
Example
Note
We currently do not support constant representation of key-value arrays. You will need to build one using the indexing operator.
NULL (and NIL)
Null values have been introduced in SIL in version 5.8.0.0, Motivation is very simple. Consider the following code, when you are required to nullify (unset) a variable
We considered this way unhealthy, therefore we introduced null (or nil)
Variable Declaration
The general syntax for declaring a variable is:
Example
Constants
Variables can be made read-only by adding the keyword "const" before the type when the variable is first defined.
If set to an array or structure, the read-only attribute will be applied to all the elements of the array or fields of the structure.
Function Declaration
In addition to the functions provided out-of-the-box by SIL, you can define your local functions (user-defined routine/function or UDRs in short) that use the following syntax:
Explicit Type Casts
Most of the time, SIL™ will attempt to do the type-casting for you automatically, however this cannot be always performed like this. These type casts allow you explicitly to convert a variable to a specific type.The general syntax for casting is:
Example
Note
Not all type casts are valid. For example it makes no sense to convert an interval to a date.
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