Coding (from Fraktal SAS Programming)

Rules?

While there is no technical reason to introduce and follow coding rules and typographical conventions, it has proven as helpful to do so depending on working context and purpose that is followed.

SAS is freedom is good news for most ad-hoc programmers aiming to have results the same minute.

SAS is freedom is bad news for all team leads and managers bearing responsibility for sustainable usage of resources and maintenance of programs written by individuals that will most likely leave some day.

Throughout the text of this tutorial we will therefore adhere to a set of rules that might seem superfluous at 1st sight but will help to catch structure and process implemented in a program without deep-diving into the code.

Standards!

SAS supports modular coding very well because code processing follows a block or “group” structure as the architects at SAS Institute Inc. would put it. Let’s directly jump into this topic:

data basix;
city='Washington'; lat="038° 054′ N"; long="077° 002′ W"; output;
city='Berlin'; lat="052° 031′ N"; long="013° 024′ O"; output;
city='Tokyo'; lat="035° 041′ N"; long="139° 046′ O"; output;
proc sort; by lat;
proc print; run;

This appears to be an easy to read and straightforward written program, and this is definitely true. And indeed, this code will complete without error messages and produce a formatted list of three cities along with their explicit latitude and longitude.

But this is not the program that is processed by SAS.

What does SAS see?

Groups

The SAS compiler processes the source code submitted in so called steps which in turn are comprised from groups of lines terminated by a semicolon. If users do not code full steps, then SAS completes the code up to a certain amount.

Lines terminated with semicolon are called statements.

Steps comprised from statements like above are called run groups.

Logically, the submitted code from the above example, will be transformed into three run groups that are executed in discrete steps. In each step syntax check and handling of user feedback is handled separately.

data basix;
city='Washington'; lat="038° 054′ N"; long="077° 002′ W"; output;
city='Berlin'; lat="052° 031′ N"; long="013° 024′ O"; output;
city='Tokyo'; lat="035° 041′ N"; long="139° 046′ O"; output;
run;

proc sort data=basix out=basix; 
by lat;
run;

proc print data=basix; 
run;

Segments

As already emphasized, SAS coded workflow is processed as sequence of blocks or groups. Since this processing structure is used everywhere in SAS, we will refer to these blocks and groups as segments throughout the remainder of this text.

Due to various languages available inside SAS, particular segments might have their very special appearance. The run group example from above is merely one of them.

Segments from different syntaxes may be hierarchically nested.

Segments may not intersect, with one exception, however.