17. Names and Displays
In addition to the normal names used thus far, there are three
further classes:
| 1) | $: is used for self-reference, allowing a verb to be defined recursively without necessarily assigning a name to it, as illustrated in Section 22. |
| 2) | The names x and y are used in explicit definition, discussed in Section 18. They denote the arguments used in explicit definition. |
| 3) | A name (such as ab_cd_) that has two underbars of which one is the final character, is a locative. Names used in a locale F can be referred to in another locale G by using the suffix F in a locative name of the form pqr_F_ , thus avoiding conflict with otherwise identical names in the locale G . See Section I of Part II for further details. |
The form of the display invoked by entering a name
alone is established by 9!:3 ,
as described in Appendix A.
For example:
mean=: +/ % # 9!:3 (4) Tree form mean +- / --- + --+- % +- # 9!:3 (5) Linear form mean +/ % #
Multiple displays are also possible:
9!:3 (5 4 2) mean +/ % # +- / --- + --+- % +- # +-----+-+-+ |+-+-+|%|#| ||+|/|| | | |+-+-+| | | +-----+-+-+
Exercises
| 17.1 | Experiment with the use of locatives. |