# Monad/dyad definition

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As discussed in the earlier section on ambivalence, all verbs had two definitions, a monad and a dyad. You have defined only a monad for centigrade. What about the dyad?

23 centigrade 32 |domain error: centigrade | 23 centigrade 32

Since you didn't provide a dyad definition, it is empty and this is treated as if the dyad had no arguments in its domain, and any arguments you give will cause a domain error.

Let's examine some simple examples of defining dyadic, monadic, and both cases.

monadminus =. 3 : 0 - y ) monadminus 5 _5 5 monadminus 3 |domain error: monadminus | 5 monadminus 3

The above defines the monad of the verb named monadminus. Applying it monadically works and applying it dyadically fails.

In one-line definitions like this you can take a shortcut and make the definition on a single line and avoid entering the special input mode that needs to be ended with the ). The following is an equivalent way of doing the above definition:

monadminus =. 3 : '- y'

The string contains the single line that makes up the definition. It is provided directly as the right argument of : instead of the 0 used earlier.

So far you have defined just the monadic case of a verb. You can also define a verb with just a dyadic definition. Instead of 3 as the left argument to : use a 4 to define the dyadic case.

dyadminus =. 4 : 'x - y' 5 dyadminus 3 2 dyadminus 5 |domain error: dyadminus | dyadminus 5

In the monad case the y name is the right argument and in the dyad case x is the left argument and y is the right.

What if you want to define both cases of a verb?

minus =. 3 : 0 - y : x - y )

The : by itself on a line separates the monad and dyad definitions.

3 minus 5 _2 5 minus 3 2 minus 5 _5

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