2a: Unit Logic

++biff

Unit as argument

Applies a function b that produces a unit to the unwrapped value of unit a (u.a). If a is empty, ~ is produced.

Accepts

a is a unit.

b is a function that accepts a noun and produces a unit.

Produces

A unit.

Source

++  biff
  |*  [a=(unit) b=$-(* (unit))]
  ?~  a  ~
  (b u.a)

Examples

> (biff (some 5) |=(a=@ (some (add a 2))))
[~ u=7]

> (biff ~ |=(a=@ (some (add a 2))))
~

++bind

Non-unit function to unit, producing unit

Applies a function b to the value (u.a) of a unit a, producing a unit. Used when you want a function that does not accept or produce a unit to both accept and produce a unit.

Accepts

a is a unit.

b is a function.

Produces

A unit.

Source

++  bind
  |*  [a=(unit) b=gate]
  ?~  a  ~
  [~ u=(b u.a)]

Examples

> (bind ((unit @) [~ 97]) ,@t)
[~ u='a']

> =a |=(a=@ (add a 1))
> (bind ((unit @) [~ 2]) a)
[~ u=3]

++bond

Replace null

Replaces an empty unit b with the product of a called trap a. If the unit is not empty, then the original unit is produced.

Accepts

a is a trap.

b is a unit.

Produces

Either the product of a or the value inside of unit b.

Source

++  bond
  |*  a=(trap)
  |*  b=(unit)
  ?~  b  $:a
  u.b

Examples

    > (bex 10)
    1.024
    > ((bond |.((bex 10))) ~)
    1.024

    > ((bond |.((bex 10))) (slaw %ud '123'))
    123

++both

Group unit values into pair

Produces ~ if either a or b are empty. Otherwise, produces a unit whose value is a cell of the values of two input units a and b.

Accepts

a is a unit.

b is a unit.

Produces

A unit of the two initial values.

Source

++  both
  |*  [a=(unit) b=(unit)]
  ?~  a  ~
  ?~  b  ~
  [~ u=[u.a u.b]]

Examples

> (both (some 1) (some %b))
[~ u=[1 %b]]

> (both ~ (some %b))
~

++clap

Combine two units with function

Applies a binary function c--which does not usually accept or produce a unit-- to the values of two units, a and b, producing a unit.

If a is null, produces b. If b is null, produces a. Otherwise, produces the produce of c in a unit.

Accepts

a is a unit.

b is a unit.

c is a function that performs a binary operation.

Produces

A unit.

Source

++  clap
  |*  [a=(unit) b=(unit) c=_=>(~ |=(^ +<-))]
  ?~  a  b
  ?~  b  a
  [~ u=(c u.a u.b)]

Examples

> (clap ~ `'b' |=([a=@tD b=@tD] `tape`[a b ~]))
[~ u='b']

> (clap `'a' ~ |=([a=@tD b=@tD] `tape`[a b ~]))
[~ u='a']

> (clap `'a' `'b' |=([a=@tD b=@tD] `tape`[a b ~]))
[~ u="ab"]

++clef

Compose two units with function

Applies a binary function c--which does not usually accept units-- to the values of two units, a and b, producing a unit.

If a or b are null, produces null. Otherwise, produces the produce of c.

Accepts

a is a unit.

b is a unit.

c is a gate that takes a cell and produces a unit.

Produces

A unit.

Source

++  clef
  |*  [a=(unit) b=(unit) c=_=>(~ |=(^ `+<-))]
  ?~  a  ~
  ?~  b  ~
  (c u.a u.b)

Examples

> (clef ~ `'b' |=([a=@tD b=@tD] `(unit tape)`[~ [a b ~]]))
~

> (clef `'a' ~ |=([a=@tD b=@tD] `(unit tape)`[~ [a b ~]]))
~

> (clef `'a' `'b' |=([a=@tD b=@tD] `(unit tape)`[~ [a b ~]]))
[~ "ab"]

++drop

Unit to list

Makes a ++list of the unwrapped value (u.a) of a unit a.

Accepts

a is a unit.

Produces

A list.

Source

++  drop
  |*  a=(unit)
  ?~  a  ~
  [i=u.a t=~]

Examples

> =a ((unit @) [~ 97])
> (drop a)
[i=97 t=~]

> =a ((unit @) [~])
> (drop a)
~

++fall

Give unit a default value

Produces a default value b for a unit a in cases where a is null.

Accepts

a is a unit.

b is a noun that's used as the default value.

Produces

Either a noun b or the unwrapped value of unit a.

Source

++  fall
  |*  [a=(unit) b=*]
  ?~(a b u.a)

Examples

> (fall ~ 'a')
'a'
> (fall [~ u=0] 'a')
0

++flit

Make filter

Accepts gate a which produces a ?. Applies a to b, producing b wrapped in a unit if true, otherwise produces null.

+flit is a wet gate that takes a and produces a new wet gate that takes b.

Accepts

a is a gate which produces ?, and is the sample of the outer wet gate.

b is any noun, and is the sample of the inner wet gate.

Produces

(unit [type]), where [type] is the type of b.

Source

++  flit
  |*  a=$-(* ?)
  |*  b=*
  ?.((a b) ~ [~ u=b])

Examples

> =f (flit |=(=@ud ?:(=(ud 1) %.y %.n)))
> (f 1)
[~ 1]
> (f 2)
~

++hunt

First of units

Apply binary gate ord, which produces a ?, to units a and b. Produce a if true and b if false. If a is null, produce b. If b is null, produce a.

This allows selecting between two units by some rule.

Accepts

ord is a $-(^ ?) - a binary gate that produces ?.

a is a unit.

b is a unit.

Produces

A unit.

Source

++  hunt
  |*  [ord=$-(^ ?) a=(unit) b=(unit)]
  ^-  %-  unit
      $?  _?>(?=(^ a) u.a)
          _?>(?=(^ b) u.b)
      ==
  ?~  a  b
  ?~  b  a
  ?:((ord u.a u.b) a b)

Examples

> (hunt gte ~ `20)
[~ 20]

> (hunt gte `10 ~)
[~ 10]

> (hunt gte `10 `20)
[~ 20]

++lift

Curried bind

Accepts function a and produces a function that accepts unit b to which it applies a. Used when you want a function that does not accept or produce a unit to both accept and produce a unit.

Accepts

a is a mold.

b is a unit.

Produces

A unit.

Source

++  lift
  |*  a=mold
  |*  b=(unit)
  (bind b a)

Examples

> ((lift dec) `(unit @)`~)
~

> ((lift dec) `(unit @)`[~ 20])
[~ 19]

++mate

Choose

Accepts two units a and b whose values are expected to be equivalent. If either is empty, then the value of the other is produced. If neither are empty, it asserts that both values are the same and produces that value. If the assertion fails, ++mate crashes with 'mate' in the stack trace.

Accepts

a is a unit.

b is a unit.

Produces

A unit or crash.

Source

++  mate
  |*  [a=(unit) b=(unit)]
  ?~  b  a
  ?~  a  b
  ?.(=(u.a u.b) ~>(%mean.'mate' !!) a)

Examples

> =a ((unit @) [~ 97])
> =b ((unit @) [~ 97])
> (mate a b)
[~ 97]

> =a ((unit @) [~ 97])
> =b ((unit @) [~])
> (mate a b)
[~ 97]

> =a ((unit @) [~ 97])
> =b ((unit @) [~ 98])
> (mate a b)
! 'mate'
! exit

++need

Unwrap unit

Retrieve the value from a unit and crash if the unit is null.

Accepts

a is a unit.

Produces

Either the unwrapped value of a (u.a), or crash.

Source

++  need
  ~/  %need
  |*  a=(unit)
  ?~  a  ~>(%mean.'need' !!)
  u.a

Examples

> =a ((unit [@t @t]) [~ ['a' 'b']])
> (need a)
['a' 'b']

> =a ((unit @ud) [~ 17])
> (need a)
17

> =a ((unit @) [~])
> (need a)
! exit

++some

Wrap value in a unit

Takes any noun a and produces a unit with the value set to a.

Accepts

a is a noun.

Produces

A unit.

Source

++  some
  |*  a=*
  [~ u=a]

Examples

> (some ['a' 'b'])
[~ u=['a' 'b']]

> (some &)
[~ u=%.y]