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HPCCSystems Solutions Lab

ECL Syntax


  • Definition operator is :=
  • Terminator for statement is ;
 Val1 := 12;
 Val2 := 65;

 Result := Val1 + Val2;

Comment Out

Single Line

// is used to comment out one line.

// One line is commented out
// X + Y = Z

Block comment

/* ..... */ is used for block commenting out.

/* This is a block comment.
    It can be used to comment out multiple lines.*/

Field Access

You can use of to access dataset fields and definitions.

  • dataset.fieldName Referencing an attribute from a module
  • moduleName.definition Referencing a field from dataset


Statement Types

There are two types of coding in ECL. Definitions and Actions.


Action vs Definition Examples.
STRING  Def1  := 'OUTPUT turns definition ';
STRING  Def2  := 'to action.';

// Action: String concatenation 
Def1 + Def2;

Val1 := 12;
Val2 := 50; 

// Definition
SomeResult := Val1 + Val2;

// Action: print result
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Assigning an expression to an attribute. Definitions can’t not be executing unless it is wrapped in an action and are defined by :=. Let’s take a look at an example:

Val := 23; is a Definition. Attribute Val is defined and value 23 is assigned to it. To turn Val to an action we can wrap it in an OUTPUT.

OUTPUT(Val); is an Action and result would be 23.

[attrib_type] attrib_name := value
attrib_typeOptional, compiler can infer it from Definition.
attrib_nameThe name by which the Definition will be invoked
valueAssigned value to the Definition.


Action simply means “do something.” Actions trigger execution of a workunit that produces results.

OUTPUT('this is an action');


Action vs Definition Examples.

// Defining an attribute
str := 'Hello Word';

// Turning it into Action
OUTPUT(str, NAMED('My_First_Program'));

// Defining an Action
NumOne := MAX(1,2,5,6);

// Turning to Action
OUTPUT(NumOne, NAMED('ActionThis'));

// Simple Actions, followings produce result
'my first ECL code';
1 + 4 + 5;
2 * 3;
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