Word Formation

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The monad ;: can be useful in figuring out what the words are in a sentence. The word formation primitive takes a string as its right argument, splits it into words, and returns a result with each word in a box. For now, don't worry about what the boxes are, just note how visually helpful they are. You'll learn about boxes in later sections.

   ;: '2 + 3'
+-----+
|2|+|3|
+-----+
   ;: '2.5 + 3e4'
+---+-+---+
|2.5|+|3e4|
+---+-+---+
   ;: 'a =. 1 2 3'
+-+--+-----+
|a|=.|1 2 3|
+-+--+-----+
   ;: 'test + 123 NB. this is a comment'
+----+-+---+---------------------+
|test|+|123|NB. this is a comment|
+----+-+---+---------------------+
   ;: 'def =. ''testing 1 2 3'''
+---+--+---------------+
|def|=.|'testing 1 2 3'|
+---+--+---------------+

Note that the following are all J words and each goes in its own box:

2.5
3e4
=.
1 2 3
test
NB. this is a comment
'testing 1 2 3'

It might surprise you that constants such as 1 2 3 and 'testing 1 2 3' are J words. This is an important point and understanding it is necessary in reading and writing J sentences.

If you are ever puzzled by a J sentence (it could happen), one of the things you can do is apply ;: to it to be sure you know the words. You can then worry about the meanings of those words.

Look up ;: in the NuVoc. The informal name for ;: is word formation.

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