Natural is a fourth-generation programming language from Software AG. It is largely used for building databases output in plain text form, for example.
* Hello World in NATURAL WRITE 'Hello World!' ENDIt has the ESCAPE TOP flow control instruction, which is similar to continue in C, C++, Java and several other languages, except that it also works within subroutines to both return from the routine and then continue the calling statement's processing loop.
Like continue, it avoids large amounts of indentation levels when using nested instruction blocks inside any loop.
Example with ESCAPE TOP:
DEFINE DATA LOCAL 1 I (N3) /* 3 digits without decimals END-DEFINE FOR I = 2 TO 100 IF (I / 2 * 2) = I AND I > 2 WRITE 'Number' I 'is divisible by 2' ESCAPE TOP END-IF IF (I / 3 * 3) = I AND I > 3 WRITE 'Number' I 'is divisible by 3' ESCAPE TOP END-IF IF (I / 5 * 5) = I AND I > 5 WRITE 'Number' I 'is divisible by 5' ESCAPE TOP END-IF IF (I / 7 * 7) = I AND I > 7 WRITE 'Number' I 'is divisible by 7' ESCAPE TOP END-IF IF (I / 11 * 11) = I AND I > 11 WRITE 'Number' I 'is divisible by 11' ESCAPE TOP END-IF WRITE 'Number' I 'is prime' END-FOR ENDThe levels of indentation can be automatically adjusted with the STRUCT command in the Natural Editor.
The same example, without ESCAPE TOP:
DEFINE DATA LOCAL 1 I (N3) /* 3 digits without decimals END-DEFINE FOR I = 2 TO 100 IF (I / 2 * 2) = I AND I > 2 WRITE 'Number' I 'is divisible by 2' ELSE IF (I / 3 * 3) = I AND I > 3 WRITE 'Number' I 'is divisible by 3' ELSE IF (I / 5 * 5) = I AND I > 5 WRITE 'Number' I 'is divisible by 5' ELSE IF (I / 7 * 7) = I AND I > 7 WRITE 'Number' I 'is divisible by 7' ELSE IF (I / 11 * 11) = I AND I > 11 WRITE 'Number' I 'is divisible by 11' ELSE WRITE 'Number' I 'is prime' END-IF END-IF END-IF END-IF END-IF END-FOR ENDAnother powerful flow control instruction command is the ESCAPE BOTTOM, which is similar to ESCAPE TOP except that it continues the processing from end of the calling statement's processing loop. Example with ESCAPE BOTTOM:
One trait that sets Natural apart from most other languages is its rich syntax. For example, many languages have a simple switch case statement that can be used to replace nested IF statements pertaining to a single variable; in C-like languages, it is prone to logic errors since it is necessary to BREAK out of the statement programatically. Natural has a much cleaner/richer DECIDE statement which is easier to understand and code. Here is an example:
DECIDE ON FIRST VALUE MARITAL-STATUS VALUE 'M' DESC := 'Married' VALUE 'D' DESC := 'Divorced' VALUE 'W' DESC := 'Widowed' ANY ONCE-MARRIED := TRUE NONE DESC := 'Single' END-DECIDEFamous quotes containing the word natural:
“Natural knowledge, seeking to satisfy natural wants, has found the ideas which can alone still spiritual cravings. I say that natural knowledge, in desiring to ascertain the laws of comfort, has been driven to discover those of conduct, and to lay the foundations of a new morality.”
—Thomas Henry Huxley (1825–95)
“To her, my lord,
Was I betrothed ere I saw Hermia;
But like a sickness did I loathe this food.
But, as in health come to my natural taste,
Now I do wish it, love it, long for it,
And will for evermore be true to it.”
—William Shakespeare (1564–1616)
“[O]ur rules can have authority over such natural rights only as we have submitted to them. The rights of conscience we never submitted, we could not submit. We are answerable for them to our God.”
—Thomas Jefferson (1743–1826)