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Minor print layout tweaks, and minor content fixes

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Tony Garnock-Jones 2018-09-24 16:08:48 +01:00
parent b656df8632
commit 4716b4f4e9
1 changed files with 35 additions and 43 deletions
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syndicate/mc/preserve.md
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@ -5,12 +5,15 @@
body { font-family: palatino, "Palatino Linotype", "Palatino LT STD", "URW Palladio L", "TeX Gyre Pagella", serif; } body { font-family: palatino, "Palatino Linotype", "Palatino LT STD", "URW Palladio L", "TeX Gyre Pagella", serif; }
@media screen { @media screen {
body { padding-top: 2rem; max-width: 40em; margin: auto; font-size: 120%; } body { padding-top: 2rem; max-width: 40em; margin: auto; font-size: 120%; }
hr { display: none; }
} }
@media print { @media print {
@page { margin: 1.5cm; } @page { margin: 4rem 4rem 4.333rem 3rem; }
body { margin-left: 2rem; margin-right 2rem; } body { margin-left: 2rem; margin-right 2rem; }
h1, h2 { page-break-before: always } h1, h2 { page-break-before: always; margin-top: 0; }
h1:first-of-type, h2:first-of-type { page-break-before: auto; } h1:first-of-type, h2:first-of-type { page-break-before: auto; }
hr+* { page-break-before: always; margin-top: 0; }
hr { display: none; }
} }
h1, h2, h3, h4, h5, h6 { margin-left: -1rem; color: #4f81bd; } h1, h2, h3, h4, h5, h6 { margin-left: -1rem; color: #4f81bd; }
h2 { border-bottom: solid #4f81bd 1px; } h2 { border-bottom: solid #4f81bd 1px; }
@ -41,9 +44,9 @@ Preserves also supports the usual suite of atomic and compound data
types, in particular including *binary* data as a distinct type from types, in particular including *binary* data as a distinct type from
text strings. text strings.
Finally, Preserves defines precisely how to compare two values with Finally, Preserves defines precisely how to *compare* two values.
each other in terms of the data model, not in terms of syntax or of Comparison is based on the data model, not on syntax or on data
the data structures of any particular implementation language. structures of any particular implementation language.
[^macro-expressiveness]: By "expressive" I mean *macro-expressive* [^macro-expressiveness]: By "expressive" I mean *macro-expressive*
in the sense of Felleisen's 1991 paper, "On the Expressive Power in the sense of Felleisen's 1991 paper, "On the Expressive Power
@ -66,6 +69,9 @@ definition of the *values* that we want to work with and give them
meaning independent of their syntax. We will treat syntax separately, meaning independent of their syntax. We will treat syntax separately,
later in this document. later in this document.
Our `Value`s fall into two broad categories: *atomic* and *compound*
data.
Value = Atom Value = Atom
| Compound | Compound
@ -82,14 +88,6 @@ later in this document.
| Set | Set
| Dictionary | Dictionary
Our `Value`s fall into two broad categories: *atomic* and *compound*
data.[^inspiration]
[^inspiration]: This design was loosely inspired by S-expressions,
as seen in Lisp, Scheme, [SPKI/SDSI][sexp.txt], and many others,
as well as by the ML type system, as seen in languages such as
SML, OCaml, Haskell, Rust, and many others.
**Total order.**<a name="total-order"></a> As we go, we will **Total order.**<a name="total-order"></a> As we go, we will
incrementally specify a total order over `Value`s. Two values of the incrementally specify a total order over `Value`s. Two values of the
same kind are compared using kind-specific rules. The ordering among same kind are compared using kind-specific rules. The ordering among
@ -126,10 +124,10 @@ examples of `SignedInteger`s using standard mathematical notation.
### Unicode strings. ### Unicode strings.
A `String` is a sequence of Unicode A `String` is a sequence of Unicode
[code-point](http://www.unicode.org/glossary/#code_point)s. Two [code-point](http://www.unicode.org/glossary/#code_point)s. `String`s
`String`s are compared lexicographically, code-point by are compared lexicographically, code-point by
code-point.[^utf8-is-awesome] We will write examples of `String`s as code-point.[^utf8-is-awesome] We will write examples of `String`s as
text surrounded by double-quotes “`"`” using a monospace font. text surrounded by quotes “`"`”.
[^utf8-is-awesome]: Happily, the design of UTF-8 is such that this [^utf8-is-awesome]: Happily, the design of UTF-8 is such that this
gives the same result as a lexicographic byte-by-byte comparison gives the same result as a lexicographic byte-by-byte comparison
@ -139,33 +137,27 @@ text surrounded by double-quotes “`"`” using a monospace font.
the string containing the three Unicode code-points `z` (0x7A), `水` the string containing the three Unicode code-points `z` (0x7A), `水`
(0x6C34) and `𝄞` (0x1D11E); `""`, the empty string. (0x6C34) and `𝄞` (0x1D11E); `""`, the empty string.
**Normalization forms.** Unicode defines multiple
[normalization forms](http://unicode.org/reports/tr15/) for text. No
particular normalization form is required for `String`s;
[see below](#normalization-forms).
### Binary data. ### Binary data.
A `ByteString` is an ordered sequence of zero or more integers in the A `ByteString` is an ordered sequence of zero or more eight-bit bytes.
inclusive range [0..255]. `ByteString`s are compared `ByteString`s are compared lexicographically. We will only write
lexicographically, byte by byte. We will only write examples of examples of `ByteString`s that contain bytes denoting printable ASCII
`ByteString`s that contain bytes mapping to printable ASCII characters, using “`#"`” as an open-quote and “`"`” as a close-quote
characters, using “`#"`” as an opening quote mark and “`"`” as a mark.
closing quote mark.
**Examples.** The `ByteString` containing the integers 65, 66 and 67 **Examples.** The `ByteString` containing the integers 65, 66 and 67
(corresponding to ASCII characters `A`, `B` and `C`) is written as (corresponding to ASCII characters `A`, `B` and `C`) is written as
`#"ABC"`. The empty `ByteString` is written as `#""`. **N.B.** Despite `#"ABC"`. The empty `ByteString` is written as `#""`. **N.B.** Despite
appearances, these are *binary* data. appearances, these are *binary* data.
### Symbols or identifiers. ### Symbols.
Programming languages like Lisp and Prolog frequently use string-like Programming languages like Lisp and Prolog frequently use string-like
values called *symbols*. Here, a `Symbol` is, like a `String`, a values called *symbols*. Here, a `Symbol` is, like a `String`, a
sequence of Unicode code-points, intended to represent an identifier sequence of Unicode code-points representing an identifier of some
of some kind. `Symbol`s are also compared lexicographically by kind. `Symbol`s are also compared lexicographically by code-point. We
code-point. We will write examples including only non-empty sequences will write examples including only non-empty sequences of
of non-whitespace characters, using a monospace font without quotation non-whitespace characters, using a monospace font without quotation
marks. marks.
**Examples.** `hello-world`; `utf8-string`; `exact-integer?`. **Examples.** `hello-world`; `utf8-string`; `exact-integer?`.
@ -176,8 +168,6 @@ There are exactly two `Boolean` values, “false” and “true”. The
“false” value compares less-than the “true” value. We write `#f` for “false” value compares less-than the “true” value. We write `#f` for
“false”, and `#t` for “true”. “false”, and `#t` for “true”.
**Examples.** `#f`; `#t`.
### IEEE floating-point values. ### IEEE floating-point values.
A `Float` is a single-precision IEEE 754 floating-point value; a A `Float` is a single-precision IEEE 754 floating-point value; a
@ -345,6 +335,8 @@ representation:[^some-encodings-unused]
Each specific type of data defines its own rules for this format. Each specific type of data defines its own rules for this format.
---
#### Encoding data of known length (format B) #### Encoding data of known length (format B)
A `Repr` where the length of the `Value` to be encoded is variable but A `Repr` where the length of the `Value` to be encoded is variable but
@ -416,7 +408,7 @@ Applications *SHOULD* prefer the known-length format for encoding
#### Application-specific short form for labels #### Application-specific short form for labels
Any given protocol using Preserves may additionally define an Any given protocol using Preserves may additionally define an
interpretation for `n ∈ {0,1,2}`, mapping each *short form label interpretation for `n`∈{0,1,2}, mapping each *short form label
number* `n` to a specific record label. When encoding `m` fields with number* `n` to a specific record label. When encoding `m` fields with
short form label number `n`, format B becomes short form label number `n`, format B becomes
@ -583,7 +575,7 @@ short form label number 0 to label `discard`, 1 to `capture`, and 2 to
| `(observe (speak (discard) (capture (discard))))` | A1 B3 75 73 70 65 61 6B 80 91 80 | | `(observe (speak (discard) (capture (discard))))` | A1 B3 75 73 70 65 61 6B 80 91 80 |
| `[1 2 3 4]` (format B) | C4 11 12 13 14 | | `[1 2 3 4]` (format B) | C4 11 12 13 14 |
| `[1 2 3 4]` (format C) | 2C 11 12 13 14 3C | | `[1 2 3 4]` (format C) | 2C 11 12 13 14 3C |
| `[-2 -1 0 1]` | C4 1E 1F 40 11 | | `[-2 -1 0 1]` | C4 1E 1F 10 11 |
| `"hello"` (format B) | 55 68 65 6C 6C 6F | | `"hello"` (format B) | 55 68 65 6C 6C 6F |
| `"hello"` (format C, 2 chunks) | 25 52 68 65 53 6C 6C 6F 35 | | `"hello"` (format C, 2 chunks) | 25 52 68 65 53 6C 6C 6F 35 |
| `"hello"` (format C, 5 chunks) | 25 52 68 65 52 6C 6C 50 50 51 6F 35 | | `"hello"` (format C, 5 chunks) | 25 52 68 65 52 6C 6C 50 50 51 6F 35 |
@ -708,20 +700,20 @@ form label number 1 were chosen, the second example above, `(mime
text/plain "ABC")`, would be encoded with "92" in place of "B3 74 6D text/plain "ABC")`, would be encoded with "92" in place of "B3 74 6D
69 6D 65". 69 6D 65".
### Text ### Unicode normalization forms
#### Normalization forms Unicode defines multiple
[normalization forms](http://unicode.org/reports/tr15/) for text.
In order for users to unambiguously signal or require a particular While no particular normalization form is required for `String`s,
[normalization form](http://unicode.org/reports/tr15/), we define a users may need to unambiguously signal or require a particular
`NormalizedString`, which is a `Record` labelled with normalization form. A `NormalizedString` is a `Record` labelled with
`unicode-normalization` and having two fields, the first of which is a `unicode-normalization` and having two fields, the first of which is a
`Symbol` specifying the normalization form used (e.g. `nfc`, `nfd`, `Symbol` specifying the normalization form used (e.g. `nfc`, `nfd`,
`nfkc`, `nfkd`), and the second of which is a `String` whose `nfkc`, `nfkd`), and the second of which is a `String` whose
underlying code point representation *MUST* be normalized according to underlying code point representation *MUST* be normalized according to
the named normalization form. the named normalization form.
#### IRIs (URIs, URLs, URNs, etc.) ### IRIs (URIs, URLs, URNs, etc.)
An `IRI` is a `Record` labelled with `iri` and having one field, a An `IRI` is a `Record` labelled with `iri` and having one field, a
`String` which is the IRI itself and which *MUST* be a valid absolute `String` which is the IRI itself and which *MUST* be a valid absolute