3.0 KiB
barcab, |_
, %brcb
Door: core with sample
|_
is a synthetic rune that produces a %gold
door with
sample p
and arms q
. The list must be closed with a --
.
|_
is similar to |%
, but defines a sample for the set of arms it
contains. Moreover, |_
only accepts dry or %elm
arms. Put
simply, type checking on these arms is performed on the input before
computation. For more on variance, see the glossary entry and the
examples below.
See also
barcen, |%
, %brcn
barfas, |/
, %brfs
Produces
Twig: [%brcb p=tile q=(map term foot)]
Sample
p
is a tile. q
is a map
with ++term
keys and
++foot
values.
Tall form
|_ p
++ p.n.q
q.n.q
--
Wide form
None
Irregular form
None
Examples
/~zod/try=> =mol
|_ a=@ud
++ succ +(a)
++ prev (dec a)
--
/~zod/try=> ~(succ mol 1)
2
/~zod/try=> ~(succ mol ~(succ mol ~(prev mol 5)))
6
In this example we create a door mol
that operates on a @ud
,
a
. We add two arms to our door, ++succ
and ++prev
, and invoke them
with the irregular form of %~
. Doors are commonly invoked with
%~
, irregular form ~(arm door sample)
, which replaces the door's
sample and pulls the specified arm.
/~zod/try=> =kom
|_ a=(list)
++ hed -.a
++ tal +.a
--
new var %kom
/~zod/try=> =kot
|/ a=(list)
+- hed -.a
+- tal +.a
--
new var %kot
/~zod/try=> ~(tal kom "abc")
t=~[98 99]
/~zod/try=> ~(tal kot "abc")
t="bc"
/~zod/try=> ~(tal kot [1 2 3 ~])
[2 3 ~]
/~zod/try=> ~(tal kom [1 2 3 ~])
t=~[2 3]
Here we're demonstrating the difference between |_
and |/
. We create
a nearly identical door using both runes, each with an arm that produces
the tail of the sample, a
. You can see that our wet gates use the
sample as a tile to produce well-typed output.
++ ne
|_ tig=@
++ d (add tig '0')
++ x ?:((gte tig 10) (add tig 87) d)
++ v ?:((gte tig 10) (add tig 87) d)
++ w ?:(=(tig 63) '~' ?:(=(tig 62) '-' ?:((gte tig 36) (add tig 29) x)))
--
::
++ne
is used to print a single digit in base 10, 16, 32, or 64 and is
a part of the hoon standard library. You can find it in hoon.hoon
.
|_
is very commonly used throughout our standard library for groups of
arms who all take the same sample.
~zod/try=> ~(x ne 12)
99
~zod/try=> `@t`~(x ne 12)
'c'
~zod/try=> `@ux`12
0xc
Here we put ++ne
to work a bit. Our first call renders 12 in base 16.
Since 99
is within the ASCII character range, we can cast it to a
@t
and get 'c'
. Conveniently, casting 12
to a @ux
results in 0xc
.