urbit/base/pub/doc/hoon/library/2eg.md

section 2eG, parsing (whitespace)

++dog

. optional gap

++  dog  ;~(plug dot gay)                               ::

Dot followed by an optional gap, used in numbers.

/~zod/try=> 1.234.
            703
1.234.703
~zod/try=> (scan "a.        " ;~(pfix alf dog))
[~~~. ~]

---

++doh

@p separator

++  doh  ;~(plug ;~(plug hep hep) gay)                  ::

Phonetic base phrase separator

/~zod/try=> ~nopfel-botduc-nilnev-dolfyn--haspub-natlun-lodmur-holtyd
~nopfel-botduc-nilnev-dolfyn--haspub-natlun-lodmur-holtyd
/~zod/try=> ~nopfel-botduc-nilnev-dolfyn--
            haspub-natlun-lodmur-holtyd
~nopfel-botduc-nilnev-dolfyn--haspub-natlun-lodmur-holtyd
~zod/try=> (scan "--" doh)
[[~~- ~~-] ~]
~zod/try=> (scan "--      " doh)
[[~~- ~~-] ~]

---

++dun

-- to ~

++  dun  (cold ~ ;~(plug hep hep))                      ::  -- (phep) to ~

Parse phep, --, to null, ~.

~zod/try=> (scan "--" dun)
~
~zod/try=> (dun [[1 1] "--"])
[p=[p=1 q=3] q=[~ u=[p=~ q=[p=[p=1 q=3] q=""]]]]

---

++duz

== to ~

++  duz  (cold ~ ;~(plug tis tis))                      ::  == (stet) to ~

Parse stet, ==, to null ~.

~zod/try=> (scan "==" duz)
~
~zod/try=> (duz [[1 1] "== |=..."])
[p=[p=1 q=3] q=[~ u=[p=~ q=[p=[p=1 q=3] q=" |=..."]]]]

---

++gah

Newline or ' '

++  gah  (mask [`@`10 ' ' ~])                           ::  newline or ace

Whitespace component, either newline or space.

/~zod/try=> ^-  *  ::  show spaces
            """
               -
             -
              -
            """
[32 32 32 45 10 32 45 10 32 32 45 0]
/~zod/try=> ^-  *
            """

            """
[32 32 32 10 32 10 32 32 0]
/~zod/try=> ^-  (list ,@)
            %-  scan  :_  (star gah)
            """

            """
~[32 32 32 10 32 10 32 32]

---

++gap

Plural whitespace

++  gap  (cold ~ ;~(plug gaq (star ;~(pose vul gah))))  ::  plural whitespace

Separates tall runes

---

++gaq

End of line

++  gaq  ;~  pose                                       ::  end of line
             (just `@`10)
             ;~(plug gah ;~(pose gah vul))
             vul
         ==

Two spaces, a newline, or comment.

---

++gaw

Classic whitespace

++  gaw  (cold ~ (star ;~(pose vul gah)))               ::  classic white

Terran whitespace

---

++gay

Optional gap.

++  gay  ;~(pose gap (easy ~))                          ::

Optional gap.

---

++vul

++  vul  %-  cold  :-  ~                                ::  comments
         ;~  plug  col  col
           (star prn)
           (just `@`10)
         ==

Parse comments and produce a null. Note that a comment must be ended with a newline character.

~zod/try=> (scan "::this is a comment \0a" vul)
~
~zod/try=> (scan "::this is a comment " vul)
! {1 21}
! exit

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