2.5 KiB
bardot, |.
, %brdt
Trap
|.
, is a synthetic hoon that produces a dry %gold
trap. A
trap is a door
with one only arm $
, the empty name.
The default action performed on a trap is kicking it by pulling the arm
$
. |.
is similar to |=
with no arguments. You can think of |.
as
a function that takes no inputs.
See also
barhep, |-
, %brhp](#brhp) [bartis, |=
, %brts
Produces
Twig: [%brdt p=twig]
Sample
p
is a ++twig
.
Tall form
|. p
Wide form
|.(p)
Irregular form
None
Examples
/~zod/try=>
=a |.(42)
changed %a
/~zod/try=>
a
< 1.yln
[ a
< 2.yqy
[ a
< 3.kii
[ a
< 2.wvx
[ a=<2.kqf 2.hng 250.qyy 41.raw 414.hhh 100.xkc 1.ypj %164>
<2.hng 250.qyy 41.raw 414.hhh 100.xkc 1.ypj %164>
]
>
<2.hng 250.qyy 41.raw 414.hhh 100.xkc 1.ypj %164>
]
>
<2.hng 250.qyy 41.raw 414.hhh 100.xkc 1.ypj %164>
]
>
<2.hng 250.qyy 41.raw 414.hhh 100.xkc 1.ypj %164>
]
>
/~zod/try=>
(a)
42
/~zod/try=>
$:a
42
This is a simple example. We assign a shell variable a
to be a trap
that simply produces the atom 42
. Printing a
prints the core and its
context. Calling a
using (
, the irregular form of %-
, produces
its value. As does pulling the arm $
from inside it using $:a
.
/~zod/try=>
=a 10
changed %a
/~zod/try=>
=b |. (add a 2)
changed %b
/~zod/try=>
(b)
12
In this case we assign a variable a
to be 10
, and create a trap b
to add 2
to it. This is a trivial example, but is meant to show that
traps are useful when you need a gate that only operates on values that
are already in its context.
/~zod/try=>
=loop =+ reps=10
=+ step=0
=+ outp=0
|.
?: =(step reps)
outp
$(outp (add outp 2), step +(step))
changed %loop
/~zod/try=> (loop)
20
Expanding on our previous example, we create a trap with three local
variables, reps
, step
, and outp
. We use a trap to create a loop,
testing each time if step
is equal to reps
, if so producing outp
otherwise calling our trap again with outp
replaced with outp+2
, and
step
incremented.