ketlus, `^+`, %ktls

Cast to type

Syntax

^+ is a natural rune that casts the product of q to the type of p, verifying that it contains the type of q. ^+ is similar to ^-, but doesn't bunt the subject. Most often we use ^+ to cast when our type is already defined by something inside our context.

kethep, `^-`, %kthp

Produces

Twig: [%ktls p=twig q=twig]

Sample

p is a twig. q is a twig.

Tall form

^+  p
    q

Wide form

^+(p q)

Irregular form

None

Examples

~zod/try=> (add 90 7)
97
~zod/try=> ^+('any text' (add 90 7))
'a'

Here we use a cord (which could be any cord), 'any text' to cast our result to a '++cord'.

/~zod/try=>  =cor  |=  a=[q=@ta r=@ s=@]
                   [(cat 3 'new' q.a) (add r.a s.a) (sub r.a s.a)]
new var %cor
/~zod/try=> (cor 'start' 6 3)
[8.390.876.208.525.960.558 9 3]
/~zod/try=>  =cor  |=  a=[q=@ta r=@ s=@]
                   ^+  a
                   [(cat 3 'new' q.a) (add r.a s.a) (sub r.a s.a)]
changed %cor
/~zod/try=> (cor 'start' 6 3)
[q=~.newstart r=9 s=3]

In this example we create a gate cor and lightly manipulate the tuple it takes as a sample: we prepend 'new' to its first member, produce the sum of the latter two as the second, and the differene as the third.

In the first call you can see that our type information is lost, and we produce our cord as an atom. By adding a ^+ a we cast the result to our input, and type information is retained.

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ketlus, ^+, %ktls