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docs/tour/types: simplicity and tone edit
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Page-specific notes:
* types:
- change plaintext hierarchy diagram to mermaid
- include top and bottom
- explain "cue eval" as we've avoided it until now
* bottom:
- change values in the example so they pop more visibly
- explain what the example is showing
* top: [new page]
* numbers:
- move some prose into the example's comments
- mention number type
- align tour with spec: `4` is *not* compatible with `float`.
- add examples of float-related sugar
- move mention of arbitrary precision into here, from
docs/tour/types/bounddef/
* stringlit:
- rename to mirror "Bytes"
- remove comparison to JSON as it feels out of place
- include interpolation in the example
* stringraw:
- expand example to show comparative versions of the same string with
different delimiters
* bytes:
- plain text table changed to markdown
- include mention of how to emit a stringified byte array to help
avoid newcomer frustration
- example expanded to include the same string being output as a string
and as bytes' base64, to show the behaviour more clearly
- include string interpolation of bytes to demo "how to display some
bytes that you know aren't binary data, as a string"
- include multiple examples of both hex and octal escapes, and
demonstrate their equivalence via unification
* structs:
- renamed from /optional; alias added
- moved ahead of closed and defs to permit for a more natural flow
through learning struct concepts
- example is changed from a definition to a regular field, as this
page now precedes definitions' page.
- updated so it's suitable to accept inbound links that
previously targeted the language guide
* closed:
- updated so it's suitable to accept inbound links that
previously targeted the language guide
* defs:
- updated to be a 90% copy of docs/tour/basics/definitions/, as that
content is already written. Examples differ.
* disjunctions:
- revise awkward wording of first sentence, as it's really jarring
until the 3rd or 4th read through
- stop explaining the example via the prose; use cue-eval-i instead to
demonstrate evaluation failure
- expand example's disjunction to include 4 values, so as to demo the
syntax beyond just 2 elements
* defaults:
- add explanation of why defaults exist, what CUE does with a default,
and when
- reuse "options" language from preceding page
- make example abstract
- include a 3-way disjunction so it's not implied that the default
has to unify with the non-default
* sumstruct:
- show CUE in action in the example
* bounds:
- more narrative example, including a multi-constraint field
- removed the sentence "The bound is defined for all values for which
the corresponding comparison operation is defined", as it feels a
little too technical for the tour
* bounddef:
- move mention of arbitrary precision to docs/tour/types/numbers/
- reword "no unsigned integer type" more positively
- use cue vet for examples
- make all examples fail
* lists:
- expand explanation
- change example to be more narrative, with less prose required for
explanation
- begin the examples with common, concrete use cases, so users can get
what they need from this longer set of eamples more easily, whilst
still demonstrating important syntactic detail nearer the end
- include sufficient distinct examples so that the various syntaxes
implied by the prose have concrete visualisations
- include examples of two failure modes that can confuse newcomers
* templates:
- mention pattern constraints
- expand example to include a disjunction-based pattern constraint,
and use top for field instantiation where possible
- opened cue-lang/cue#2916
* value-constraints: [new page]
- left as draft (i.e. not published) following feedback and awaiting
later updates
For cue-lang/docs-and-content#78
Preview-Path: /docs/tour/types/types/
Preview-Path: /docs/tour/types/bottom/
Preview-Path: /docs/tour/types/top/
Preview-Path: /docs/tour/types/bounddef/
Preview-Path: /docs/tour/types/bounds/
Preview-Path: /docs/tour/types/bytes/
Preview-Path: /docs/tour/types/defaults/
Preview-Path: /docs/tour/types/structs/
Preview-Path: /docs/tour/types/closed/
Preview-Path: /docs/tour/types/defs/
Preview-Path: /docs/tour/types/disjunctions/
Preview-Path: /docs/tour/types/numbers/
Preview-Path: /docs/tour/types/lists/
Preview-Path: /docs/tour/types/stringlit/
Preview-Path: /docs/tour/types/stringraw/
Preview-Path: /docs/tour/types/sumstruct/
Preview-Path: /docs/tour/types/templates/
Signed-off-by: Jonathan Matthews <github@hello.jonathanmatthews.com>
Change-Id: Id4870cb92903bfcb7662fb236a7da2ace15a24c5
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cuelang.org/+/1177673
TryBot-Result: CUEcueckoo <cueckoo@gmail.com>
Reviewed-by: Paul Jolly <paul@myitcv.io>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,35 +1,40 @@ | ||
| --- | ||
| title: "Bottom / Error" | ||
| title: Bottom / Error | ||
| weight: 20 | ||
| --- | ||
|
|
||
| Specifying duplicate fields with conflicting values results in an error | ||
| or bottom. | ||
| _Bottom_ is a special value in CUE, denoted `_|_`, that indicates an | ||
| error such as conflicting values. | ||
| Any error in CUE results in `_|_`. | ||
| Logically all errors are equal, although errors may be associated with | ||
| metadata such as an error message. | ||
|
|
||
| Note that an error is different from `null`: `null` is a valid value, | ||
| whereas `_|_` is not. | ||
|
|
||
| {{{with code "en" "bottom"}}} | ||
| exec cue eval -i bottom.cue | ||
| cmp stdout result.txt | ||
| -- bottom.cue -- | ||
| a: 4 | ||
| a: 5 | ||
|
|
||
| l: [1, 2] | ||
| l: [1, 3] | ||
|
|
||
| list: [0, 1, 2] | ||
| val: list[3] | ||
| -- result.txt -- | ||
| a: _|_ // a: conflicting values 5 and 4 | ||
| l: [1, _|_, // l.1: conflicting values 3 and 2 | ||
| Specifying a field multiple times with conflicting values results in an error, | ||
| or **bottom**, written `_|_`. | ||
|
|
||
| Bottom is a special value in CUE, and is the value that results from any error. | ||
| Logically, all errors are equal, | ||
| although CUE may associate them with metadata such as an error message. | ||
|
|
||
| An error is *not* the same as the value `null`. | ||
| `_|_` isn't a valid value for a field, but `null` is. | ||
|
|
||
| {{{with code "en" "tour"}}} | ||
| exec cue eval -i file.cue | ||
| cmp stdout out | ||
| -- file.cue -- | ||
| a: 1 | ||
| a: 2 | ||
|
|
||
| b: [50, 100] | ||
| b: [50, 200] | ||
|
|
||
| c: [0, 1, 2] | ||
|
|
||
| d: c[5] | ||
| -- out -- | ||
| a: _|_ // a: conflicting values 2 and 1 | ||
| b: [50, _|_, // b.1: conflicting values 200 and 100 | ||
| ] | ||
| list: [0, 1, 2] | ||
| val: _|_ // val: index out of range [3] with length 3 | ||
| c: [0, 1, 2] | ||
| d: _|_ // d: invalid list index 5 (out of bounds) | ||
| {{{end}}} | ||
|
|
||
| Notice how the `-i` flag changes how `cue eval` behaves. | ||
| It causes errors to be represented as literal error values in the output, with | ||
| error messages as inline comments. | ||
| These literal `_|_` values *invalidate* the CUE that's output. |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,44 +1,43 @@ | ||
| --- | ||
| title: "Predefined Bounds" | ||
| title: Predefined Bounds | ||
| weight: 140 | ||
| --- | ||
|
|
||
| CUE numbers have arbitrary precision. | ||
| Also there is no unsigned integer type. | ||
|
|
||
| CUE defines the following predefined identifiers to restrict the bounds of | ||
| integers to common values. | ||
| integers to common values.\ | ||
| The `u`-prefixed identifiers provide similar capabilities to unsigned integer | ||
| types in other languages. | ||
|
|
||
| {{{with code "en" "defined"}}} | ||
| -- defined.cue -- | ||
| uint: >=0 | ||
| uint8: >=0 & <=255 | ||
| int8: >=-128 & <=127 | ||
| uint16: >=0 & <=65536 | ||
| int16: >=-32_768 & <=32_767 | ||
| rune: >=0 & <=0x10FFFF | ||
| uint32: >=0 & <=4_294_967_296 | ||
| int32: >=-2_147_483_648 & <=2_147_483_647 | ||
| uint64: >=0 & <=18_446_744_073_709_551_615 | ||
| int64: >=-9_223_372_036_854_775_808 & <=9_223_372_036_854_775_807 | ||
| int128: >=-170_141_183_460_469_231_731_687_303_715_884_105_728 & | ||
| <=170_141_183_460_469_231_731_687_303_715_884_105_727 | ||
| {{{with code "en" "identifiers"}}} | ||
| -- file.cue -- | ||
| uint: >=0 | ||
| uint8: >=0 & <=255 | ||
| int8: >=-128 & <=127 | ||
| uint16: >=0 & <=65536 | ||
| int16: >=-32_768 & <=32_767 | ||
| rune: >=0 & <=0x10FFFF | ||
| uint32: >=0 & <=4_294_967_296 | ||
| int32: >=-2_147_483_648 & <=2_147_483_647 | ||
| uint64: >=0 & <=18_446_744_073_709_551_615 | ||
| int64: >=-9_223_372_036_854_775_808 & <=9_223_372_036_854_775_807 | ||
| int128: >=-170_141_183_460_469_231_731_687_303_715_884_105_728 & <=170_141_183_460_469_231_731_687_303_715_884_105_727 | ||
| uint128: >=0 & <=340_282_366_920_938_463_463_374_607_431_768_211_455 | ||
| {{{end}}} | ||
|
|
||
| {{{with code "en" "failure"}}} | ||
| exec cue eval -ic bound.cue | ||
| cmp stdout result.txt | ||
| -- bound.cue -- | ||
| #positive: uint | ||
| #byte: uint8 | ||
| #word: int32 | ||
| {{{with code "en" "tour"}}} | ||
| ! exec cue vet file.cue | ||
| cmp stderr out | ||
| -- file.cue -- | ||
| import "math" | ||
|
|
||
| a: #positive & -1 | ||
| b: #byte & 128 | ||
| c: #word & 2_000_000_000 | ||
| -- result.txt -- | ||
| a: _|_ // a: invalid value -1 (out of bound >=0) | ||
| b: 128 | ||
| c: 2000000000 | ||
| a: uint & -1 | ||
| b: uint8 & 256 | ||
| c: int32 & math.Pow(2, 31) // 2^31 | ||
| -- out -- | ||
| a: invalid value -1 (out of bound >=0): | ||
| ./file.cue:3:11 | ||
| b: invalid value 256 (out of bound <=255): | ||
| ./file.cue:4:12 | ||
| c: invalid value 2147483648 (out of bound <=2147483647): | ||
| ./file.cue:5:12 | ||
| {{{end}}} |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,40 +1,46 @@ | ||
| --- | ||
| title: "Bounds" | ||
| title: Bounds | ||
| weight: 130 | ||
| --- | ||
|
|
||
| Bounds define a lower bound, upper bound, or inequality for a certain value. | ||
| They work on numbers, strings, bytes and null. | ||
|
|
||
| The bound is defined for all values for which the corresponding comparison | ||
| operation is defined. | ||
| For instance `>5.0` allows all floating point values greater than `5.0`, | ||
| whereas `<0` allows all negative numbers (int or float). | ||
|
|
||
|
|
||
| {{{with code "en" "failure"}}} | ||
| exec cue eval -ic bounds.cue | ||
| cmp stdout result.txt | ||
| -- bounds.cue -- | ||
| #rn: >=3 & <8 // type int | float | ||
|
|
||
| #ri: >=3 & <8 & int // type int | ||
|
|
||
| #rf: >=3 & <=8.0 // type float | ||
| #rs: >="a" & <"mo" | ||
|
|
||
| a: #rn & 3.5 | ||
| b: #ri & 3.5 | ||
| c: #rf & 3 | ||
| d: #rs & "ma" | ||
| e: #rs & "mu" | ||
|
|
||
| r1: #rn & >=5 & <10 | ||
| -- result.txt -- | ||
| a: 3.5 | ||
| b: _|_ // b: conflicting values int and 3.5 (mismatched types int and float) | ||
| c: 3 | ||
| d: "ma" | ||
| e: _|_ // e: invalid value "mu" (out of bound <"mo") | ||
| r1: >=5 & <8 | ||
| **Bounds** define | ||
| a lower bound, an upper bound, or inequality for a certain value, | ||
| all of which can be combined. | ||
| They work on numbers, strings, bytes, and `null`. | ||
|
|
||
| A bound is expressed using comparison operators such as `>`, `<=`, and `!=`. | ||
| It permits values where the comparison would return `true`, | ||
| and we say that *the bound is defined* for these values. | ||
|
|
||
| {{{with code "en" "tour"}}} | ||
| #nofmt https://github.com/cue-lang/cue/issues/2913 | ||
|
|
||
| exec cue eval -ic file.cue | ||
| cmp stdout out | ||
| -- file.cue -- | ||
| #floatOver5: >5.0 // type: float | ||
| #negativeNum: <0 // type: int | float | ||
| #afterL: >"L" // type: string | ||
| #notNull: !=null // type: any except null | ||
|
|
||
| zero: 0 & >10 // failure | ||
| float10: 10.0 & #floatOver5 | ||
| float5: 5.0 & #floatOver5 // failure | ||
| "num-6": -6 & #negativeNum | ||
| A: "A" & #afterL // failure | ||
| Z: "Z" & #afterL | ||
| isNull: null & #notNull // failure | ||
| isNotNull: "X" & #notNull | ||
|
|
||
| float425: 42.5 & #notNull & <100 & #floatOver5 | ||
| -- out -- | ||
| zero: _|_ // zero: invalid value 0 (out of bound >10) | ||
| float10: 10.0 | ||
| float5: _|_ // float5: invalid value 5.0 (out of bound >5.0) | ||
| "num-6": -6 | ||
| A: _|_ // A: invalid value "A" (out of bound >"L") | ||
| Z: "Z" | ||
| isNull: _|_ // isNull: conflicting values null and !=null (mismatched types null and (bool|string|bytes|func|list|struct|number)) | ||
| isNotNull: "X" | ||
| float425: 42.5 | ||
| {{{end}}} |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,27 +1,42 @@ | ||
| --- | ||
| title: "Bytes" | ||
| title: Bytes | ||
| weight: 60 | ||
| --- | ||
|
|
||
| CUE distinguishes between a `string` and a `bytes` type. | ||
| Bytes are converted to base64 when emitting JSON. | ||
| CUE distinguishes the **`bytes`** type from the `string` type. | ||
| Byte literals are defined with single quotes. | ||
| The following additional escape sequences are allowed in byte literals: | ||
|
|
||
| {{{with code "en" "escapes"}}} | ||
| -- plain.txt -- | ||
| \xnn // arbitrary byte value defined as a 2-digit hexadecimal number | ||
| \nnn // arbitrary byte value defined as a 3-digit octal number | ||
| {{{end}}} | ||
| <!-- jba: this contradicts the spec, which has \nnn (no leading zero) --> | ||
| In addition to the escape sequences permitted in string literals, | ||
| byte literals also allow these escape sequences: | ||
|
|
||
| {{< table >}} | ||
| | Sequence | Result | | ||
| | ---:| --- | | ||
| | **`\xnn`** | Arbitrary byte value defined as the 2-digit hexadecimal number "**`nn`**" | | ||
| | **`\nnn`** | Arbitrary byte value defined as the 3-digit octal number "**`nnn`**" | | ||
| {{< /table >}} | ||
|
|
||
| Bytes are represented as Base64 when exporting concrete data to a format such as JSON or YAML.\ | ||
| To avoid this, interpolate bytes inside a string value. | ||
|
|
||
| {{{with code "en" "tour"}}} | ||
| exec cue export file.cue | ||
| cmp stdout out | ||
| -- file.cue -- | ||
| aString: "A string" | ||
|
|
||
| // Multiple representations of the same underlying | ||
| // bytes, which therefore unify succesfully. | ||
| Bytes: 'A string' | ||
| Bytes: '\(aString)' | ||
| Bytes: '\x41\x20\x73\x74\x72\x69\x6e\x67' | ||
| Bytes: '\101\040\163\164\162\151\156\147' | ||
|
|
||
| {{{with code "en" "bytes"}}} | ||
| exec cue export bytes.cue | ||
| cmp stdout result.txt | ||
| -- bytes.cue -- | ||
| a: '\x03abc' | ||
| -- result.txt -- | ||
| stringBytes: "\(Bytes)" | ||
| -- out -- | ||
| { | ||
| "a": "A2FiYw==" | ||
| "aString": "A string", | ||
| "Bytes": "QSBzdHJpbmc=", | ||
| "stringBytes": "A string" | ||
| } | ||
| {{{end}}} |
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