2. CASL Variables: More Powerful Than Macro Variables

Unlike macro variables, which are just text, CASL uses dynamically typed variables (the type is defined upon assignment)⁵. The true power of CASL lies in its composite data types.

Table 2: CASL Data Types

Important Note: Arrays in CASL start at index 1 (like in SAS^©), but use curly braces {} for definition and can contain mixed data types

3. Data-Driven Programming: The DO OVER Loop

The modern and high-performance equivalent of macro loops (%DO %WHILE or loops on call execute) is the DO OVER loop in CASL. It allows for easy iteration over arrays, dictionaries, or result tables.

DO OVER Loop Syntax

• For a Dictionary: DO , OVER ;

• For an Array: DO OVER ;

• For a Table: You iterate over the rows as if it were an array.

Table 3: Macro vs. CASL Comparison for Data-Driven Programming

4. User-Defined Functions (UDFs)

Instead of writing a macro (%macro myTask; ... %mend;), you can create your own functions in CASL.

• Advantage: The code is more concise and does not require the CAS engine to generate CASL code with each call, which is more efficient.

• Persistence: By default, a CASL function only lasts for the duration of the PROC CAS procedure. To reuse them, you must save the code in a .sas© file and load it with readpath() and execute() at the beginning of your session.

Example of UDF logic: You can create a loadAllFiles(caslib) function that retrieves the list of files from a caslib and loops over them to automatically load them into memory, thus replacing dozens of lines of complex macro code.