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IML Line Pushing Contrasted with Using the Macro Facility

The SAS macro language is a language embedded in and running on top of another language; it generates text to feed the other language. Sometimes it is more convenient to generate the text by using the primary language directly rather than embedding the text generation in macros. The preceding examples show that this can even be done at execution time, whereas pure macro processing is done only at parse time. The advantage of the macro language is its embedded, yet independent, nature: it needs little quoting, and it works for all parts of the SAS language, not just IML. The disadvantage is that it is a separate language that has its own learning burden, and it uses extra reserved characters to mark its programming constructs and variables. Consider the quoting of IML versus the embedding characters of the macro facility: IML makes you quote every text constant, whereas the macro facility makes you use the special characters percent sign (%) and ampersand (&) on every macro item. There are some languages, such as REXX, that give you the benefits of both (no macro characters and no required quotes), but the cost is that the language forces you to discipline your naming so that names are not expanded inadvertently.