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preserves
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tag -> label; slot -> field

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Tony Garnock-Jones 2019-08-18 14:21:35 +01:00
parent 17368c8961
commit c7bae6eff8
1 changed files with 8 additions and 8 deletions
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@ -192,15 +192,15 @@ sorting needs to occur), but is still quite fast in general.
Finally, there is one more type that Preserves provides... but in a
sense, it's a meta-type.
=Record= objects have a tag and a series of arguments (or "slots").
=Record= objects have a label and a series of arguments (or "fields").
For example, we can make a =Date= record:
#+BEGIN_SRC preserves
<Date 2019 8 15>
#+END_SRC
In this example, the =Date= tag is a symbol; 2019, 8, and 15 are the
year, month, and date slots respectively.
In this example, the =Date= label is a symbol; 2019, 8, and 15 are the
year, month, and day fields respectively.
Why do we care about this?
We could instead just decide to encode our date data in a string,
@ -258,17 +258,17 @@ We can make as many Record types as our program need, though it is up
to our program to make sense of what these mean.
Since Preserves does not specify the =Date= itself, both the program
(or person) writing the Preserves document and the program reading it
need to have a mutual understanding of how many slots it has and what
the meaning the tag signifies for it to be of use.
need to have a mutual understanding of how many fields it has and what
the meaning the label signifies for it to be of use.
Still, there are plenty of interesting tags we can define.
Still, there are plenty of interesting labels we can define.
Here is one for an "iri", a hyperlink:
#+BEGIN_SRC preserves
<iri "https://dustycloud.org/blog/">
#+END_SRC
That's nice enough, but here's another interesting detail... tags on
That's nice enough, but here's another interesting detail... labels on
Records are usually symbols but aren't necessarily so.
They can also be strings or numbers or even dictionaries.
And very interestingly, they can also be other records:
@ -280,7 +280,7 @@ And very interestingly, they can also be other records:
"content": "Say, did you finish reading that book I lent you?"}>
#+END_SRC
Do you see it? This Record's tag is... an iri Record!
Do you see it? This Record's label is... an =iri= Record!
The link here points to a more precise term saying that "this is a
note meant to be sent around in social networks".
It is considerably more precise than just using the string or symbol