Runes

!> "zapgar"

[%zpgr p=hoon]: wrap a noun in its type.

Produces

A cell whose tail is the product of p, and whose head is the static type of p.

Syntax

Regular: 1-fixed.

Discussion

In Hoon, a dynamic type is a static type compiled at runtime. This type-noun cell is generally called a vase.

Examples

> !>(1)
[#t/@ud q=1]

If you want just the type value, use a 'type spear'. This is -:!>, i.e., the head of the cell produced by !>:

> -:!>(1)
#t/@ud

!< "zapgal"

[%zpld p=spec q=hoon]

Takes a mold and a vase and dynamically checks that the type in the vase matches the mold.

Produces

The value of vase typed with the type of the mold if possible, else a nest-fail.

Syntax

Regular: 2-fixed

Discussion

This is something like a partial inverse to the !> rune and can be used to extract a typed value from a vase.

Examples

> !<  @  !>  ~zod
0

> !<  @p  !>  0
nest-fail

> =m !>  0
> =n !>  1
> !<  [@ @]  (slop m n)
[0 1]

!: "zapcol"

[%dbug p=hoon]: turn on stack trace

Produces

The product of p unless p crashes, in which case a stack trace is given.

Syntax

Regular: 1-fixed.

!:  p=hoon

Discussion

!: is used to turn on a debugging stack trace option for any code you have in p.

Examples

> ?:(=(0 1) 123 !!)
ford: %ride failed to execute:

> !:  ?:(=(0 1) 123 !!)
/~zod/home/~2018.10.15..19.50.06..74af:<[1 5].[1 22]>
/~zod/home/~2018.10.15..19.50.06..74af:<[1 19].[1 21]>
ford: %ride failed to execute:

!. "zapdot"

Turn off stack trace for a subexpression p

Produces

The product of p. If p crashes, no stack trace entries are given for that code.

Syntax

Regular: 1-fixed.

!.  p=hoon

p is any Hoon expression.

Discussion

!. is used to turn off a debugging stack trace option for any code you have in p. This rune can be embedded under a !: rune for inner loops of your code that you don't want or need to trace. This is especially useful if a trace overflows the stack.

Examples

> %.(1 |=(a=@ ^-(@ ?:(=(a 10) !! $(a +(a))))))
ford: %ride failed to execute:

> !:  %.(1 |=(a=@ ^-(@ ?:(=(a 10) !! $(a +(a))))))
/~zod/home/~2018.10.15..20.01.21..6b0c:<[1 5].[1 49]>
/~zod/home/~2018.10.15..20.01.21..6b0c:<[1 17].[1 47]>
/~zod/home/~2018.10.15..20.01.21..6b0c:<[1 22].[1 46]>
/~zod/home/~2018.10.15..20.01.21..6b0c:<[1 36].[1 45]>
...skipping some lines...
/~zod/home/~2018.10.15..20.01.21..6b0c:<[1 17].[1 47]>
/~zod/home/~2018.10.15..20.01.21..6b0c:<[1 22].[1 46]>
/~zod/home/~2018.10.15..20.01.21..6b0c:<[1 33].[1 35]>
ford: %ride failed to execute:

> !:  %.(1 !.(|=(a=@ ^-(@ ?:(=(a 10) !! $(a +(a)))))))
/~zod/home/~2018.10.15..20.01.35..0529:<[1 5].[1 53]>
ford: %ride failed to execute:

!= "zaptis"

[%zpts p=hoon]: make the Nock formula for a Hoon expression.

Produces

The Nock generated by p.

Syntax

Regular: 1-fixed.

Discussion

Don't confuse != with a negation, !, followed by a test for equality, =(10 11).

Examples

> !=(20)
[1 20]

> !=(~zod)
[1 0]

> !=((add 2 2))
[8 [9 3.110.356 0 31] 9 2 [0 4] [7 [0 3] 1 2 2] 0 11]

Don't confuse the != rune with:

> !=(10 11)
%.y

> !=(10 10)
%.n

The syntax difference is that a test for equality takes two subexpressions, and the != rune only one.

!? "zapwut"

[%zpwt p=@ q=hoon]: restrict Hoon version.

Produces

q, if p is greater than or equal to the Hoon kelvin version. (Versions count down; the current version is 141.)

Syntax

Regular: 2-fixed.

Examples

> !?(264 (add 2 2))
4

> !?(164 (add 2 2))
4

> !?(64 (add 2 2))
! exit

!! "zapzap"

[%zpzp ~]: crash.

Produces

Nothing. Always crashes, with type %void.

Syntax

!!

Discussion

%void nests in every other type, so you can stub out anything with !!.

Examples

> !!
ford: build failed