|
| 1 | +# Syntax Variation Beauty Contest |
| 2 | + |
| 3 | +As discussed in the 2023-09-25 teleconference, we need to choose a syntax to proceed with. |
| 4 | +This page hosts various options for considering in the 2023-10-02 call. |
| 5 | + |
| 6 | +## Shorthand description of some aspects of the options |
| 7 | + |
| 8 | +Please dispute factual errors in this. The table uses multiple `-` when an option requires more than one of something. `+` is not weighted. |
| 9 | + |
| 10 | +| Option | Description | Doesn’t Nest {} | Doesn’t Need More Escapes | Doesn’t Require Quoted Pattern | Allows Unquoted Literal Operands | Counted {} works | Adds no sigils | |
| 11 | +| :----- | :------------------------------------------------------------- | :-------------- | :------------------------ | :----------------------------- | :------------------------------- | :--------------- | :------------- | |
| 12 | +| 0 | Current syntax, starts in code mode | - | + | -- | + | - | + | |
| 13 | +| 1 | Invert for text mode | - | + | + | - | + | + | |
| 14 | +| 1a | Invert for text mode, distinguish statements from placeholders | - | + | + | + | + | - | |
| 15 | +| 2 | Text first, but always code mode after code | - | + | - | - | + | + | |
| 16 | +| 3 | Use sigils for code mode | + | - | + | + | + | -- | |
| 17 | +| 3a | Use sigils for code mode, use {/} for keys | + | - | + | + | + | - | |
| 18 | +| 4 | Reducing keywords | + | --- | + | + | + | --- | |
| 19 | +| 5 | Use blocks for declarations and body | -- | - | + | - | - | - | |
| 20 | +| 5a | Use blocks for declarations but sigils for selectors | + | -- | + | - | - | - | |
| 21 | +| 6 | Use statements | -- | --- | + | + | + | - | |
| 22 | + |
| 23 | +## 0. Current |
| 24 | + |
| 25 | +This is the current syntax, |
| 26 | +including the changes introduced in [#488](https://github.com/unicode-org/message-format-wg/pull/488). |
| 27 | +The list of messages in this section also serves as the basis for all other examples. |
| 28 | + |
| 29 | +``` |
| 30 | +{Hello world!} |
| 31 | +
|
| 32 | +{Hello {$user}} |
| 33 | +
|
| 34 | +input {$var :function option=value} |
| 35 | +{Hello {$var}} |
| 36 | +
|
| 37 | +input {$var :function option=value} |
| 38 | +local $foo = {$bar :function option=value} |
| 39 | +{Hello {$var}, you have a {$foo}} |
| 40 | +
|
| 41 | +match {$foo} {$bar} |
| 42 | +when foo bar {Hello {$foo} you have a {$var}} |
| 43 | +when * * {{$foo} hello you have a {$var}} |
| 44 | +
|
| 45 | +match {$foo :function option=value} {$bar :function option=value} |
| 46 | +when a b { {$foo} is {$bar} } |
| 47 | +when x y { {$foo} is {$bar} } |
| 48 | +when * * { {$foo} is {$bar} } |
| 49 | +
|
| 50 | +input {$var :function option=value} local $foo = {$bar :function option=value}{Hello {$var}, you have a {$foo}} |
| 51 | +
|
| 52 | +match {$foo} {$bar} when foo bar {Hello {$foo} you have a {$var}} when * * {{$foo} hello you have a {$var}} |
| 53 | +
|
| 54 | +match {$foo :function option=value} {$bar :function option=value}when a b { {$foo} is {$bar} }when x y { {$foo} is {$bar} }when * * { {$foo} is {$bar} } |
| 55 | +``` |
| 56 | + |
| 57 | +## 1. Invert for Text Mode |
| 58 | + |
| 59 | +Consumes exterior whitespace. |
| 60 | + |
| 61 | +Requires dropping unquoted literal operands from the syntax. |
| 62 | + |
| 63 | +``` |
| 64 | +Hello world! |
| 65 | +
|
| 66 | +Hello {$user} |
| 67 | +
|
| 68 | +{input $var :function option=value} |
| 69 | +Hello {$var} |
| 70 | +
|
| 71 | +{input $var :function option=value} |
| 72 | +{local $foo = $bar :function option=value} |
| 73 | +Hello {$var}, you have a {$foo} |
| 74 | +
|
| 75 | +{match {$foo} {$bar}} |
| 76 | +{when foo bar} Hello {$foo} you have a {$var} |
| 77 | +{when * *} {$foo} hello you have a {$var} |
| 78 | +
|
| 79 | +{match {$foo :function option=value} {$bar :function option=value}} |
| 80 | +{when a b} {{ {$foo} is {$bar} }} |
| 81 | +{when x y} {{ {$foo} is {$bar} }} |
| 82 | +{when * *} {| |}{$foo} is {$bar}{| |} |
| 83 | +
|
| 84 | +{input $var :function option=value}{local $foo = $bar :function option=value}Hello {$var}, you have a {$foo} |
| 85 | +
|
| 86 | +{match {$foo} {$bar}}{when foo bar} Hello {$foo} you have a {$var}{when * *} {$foo} hello you have a {$var} |
| 87 | +
|
| 88 | +{match {$foo :function option=value}{$bar :function option=value}}{when a b} {{ {$foo} is {$bar} }}{when x y} {{ {$foo} is {$bar} }}{when * *} {| |}{$foo} is {$bar}{| |} |
| 89 | +``` |
| 90 | + |
| 91 | +## 1a. Invert for Text Mode, distinguish statements from placeholders |
| 92 | + |
| 93 | +Same as 1, but non-placeholder statements use a `#` prefix. |
| 94 | +This allows us to keep unquoted literal syntax. |
| 95 | + |
| 96 | +``` |
| 97 | +Hello world! |
| 98 | +
|
| 99 | +Hello {$user} |
| 100 | +
|
| 101 | +{#input $var :function option=value} |
| 102 | +Hello {$var} |
| 103 | +
|
| 104 | +{#input $var :function option=value} |
| 105 | +{#local $foo = $bar :function option=value} |
| 106 | +Hello {$var}, you have a {$foo} |
| 107 | +
|
| 108 | +{#match {$foo} {$bar}} |
| 109 | +{#when foo bar} Hello {$foo} you have a {$var} |
| 110 | +{#when * *} {$foo} hello you have a {$var} |
| 111 | +
|
| 112 | +{#match {$foo :function option=value} {$bar :function option=value}} |
| 113 | +{#when a b} {{ {$foo} is {$bar} }} |
| 114 | +{#when x y} {{ {$foo} is {$bar} }} |
| 115 | +{#when * *} {| |}{$foo} is {$bar}{| |} |
| 116 | +
|
| 117 | +{#input $var :function option=value} {#local $foo = $bar :function option=value} Hello {$var}, you have a {$foo} |
| 118 | +
|
| 119 | +{#match {$foo} {$bar}} {#when foo bar} Hello {$foo} you have a {$var} {#when * *} {$foo} hello you have a {$var} |
| 120 | +
|
| 121 | +{#match {$foo :function option=value}{$bar :function option=value}} {#when a b} {{ {$foo} is {$bar} }} {#when x y} {{ {$foo} is {$bar} }} {#when * *} {| |}{$foo} is {$bar}{| |} |
| 122 | +``` |
| 123 | + |
| 124 | +## 2. Text First, but Always Code After Code-Mode |
| 125 | + |
| 126 | +This is @mihnita's proposal, mentioned in the 2023-10-02 call. |
| 127 | +Start in text mode, but stay in code mode once you get there. |
| 128 | +Adapted @eemeli's start-in-text-mode syntax for these examples. |
| 129 | + |
| 130 | +Requires dropping unquoted literal operands from the syntax. |
| 131 | + |
| 132 | +``` |
| 133 | +Hello world! |
| 134 | +
|
| 135 | +Hello {$user} |
| 136 | +
|
| 137 | +{input $var :function option=value} |
| 138 | +{{Hello {$var}}} |
| 139 | +
|
| 140 | +{input $var :function option=value} |
| 141 | +{local $foo = $bar :function option=value} |
| 142 | +{{Hello {$var}, you have a {$foo}}} |
| 143 | +
|
| 144 | +{match {$foo} {$bar}} |
| 145 | +{when foo bar} {{Hello {$foo} you have a {$var}}} |
| 146 | +{when * *} {{{$foo} hello you have a {$var}}} |
| 147 | +
|
| 148 | +{match {$foo :function option=value} {$bar :function option=value}} |
| 149 | +{when a b} {{ {$foo} is {$bar} }} |
| 150 | +{when x y} {{ {$foo} is {$bar} }} |
| 151 | +
|
| 152 | +{input $var :function option=value}{local $foo = $bar :function option=value}{{Hello {$var}, you have a {$foo}}} |
| 153 | +
|
| 154 | +{match {$foo} {$bar}}{when foo bar} {{Hello {$foo} you have a {$var}}}{when * *}{{{$foo} hello you have a {$var}}} |
| 155 | +
|
| 156 | +{match {$foo :function option=value}{$bar :function option=value}}{when a b} { {$foo} is {$bar} }{when x y} { {$foo} is {$bar} } |
| 157 | +``` |
| 158 | + |
| 159 | +## 3. Use sigils for code mode |
| 160 | + |
| 161 | +Try to redues the use of `{`/`}` to just expressions and placeholders instead of the three |
| 162 | +uses we have now (the other use is for patterns). This requires escaping whitespace or using |
| 163 | +a placeholder for it. |
| 164 | +See [#487](https://github.com/unicode-org/message-format-wg/pull/487) for a discussion of whitespace options. |
| 165 | + |
| 166 | +The sigil `#` was chosen because `#define` type constructs are fairly common. |
| 167 | +Introduces `[`/`]` for keys. |
| 168 | + |
| 169 | +Requires escaping `#` when used as a pattern character. |
| 170 | + |
| 171 | +``` |
| 172 | +#input {$var :function option=value} |
| 173 | +Hello {$var} |
| 174 | +
|
| 175 | +#input {$var :function option=value} |
| 176 | +#local $foo = {$bar :function option=value} |
| 177 | +Hello {$var}, you have a {$foo} |
| 178 | +
|
| 179 | +#match {$foo} {$bar} |
| 180 | +#when[foo bar] Hello {$foo} you have a {$var} |
| 181 | +#when[ * *] {$foo} hello you have a {$var} |
| 182 | +
|
| 183 | +#match {$foo :function option=value} {$bar :function option=value} |
| 184 | +#when [a b] {{ {$foo} is {$bar} }} |
| 185 | +#when [x y] {||} {$foo} is {$bar} {||} |
| 186 | +#when [* *] {| |}{$foo} is {$bar}{| |} |
| 187 | +
|
| 188 | +#input {$var :function option=value}#local $foo = {$bar :function option=value}Hello {$var}, you have a {$foo} |
| 189 | +
|
| 190 | +#match {$foo} {$bar}#when[foo bar] Hello {$foo} you have a {$var}#when[* *] {$foo} hello you have a {$var} |
| 191 | +
|
| 192 | +#match {$foo :function option=value} {$bar :function option=value}#when [a b] {{ {$foo} is {$bar} }} #when [x y] {||} {$foo} is {$bar} {||}#when [* *] {| |}{$foo} is {$bar}{| |} |
| 193 | +``` |
| 194 | + |
| 195 | +## 3a. Use sigils for code mode, use `{`/`}` for keys |
| 196 | + |
| 197 | +Similar to 3, but uses braces instead of `[`/`]` square brackets for keys, reducing variation and |
| 198 | +the need for additional pattern escapes. |
| 199 | +See Slack thread. |
| 200 | + |
| 201 | +Requires `#` to be escaped in unquoted patterns. |
| 202 | + |
| 203 | +``` |
| 204 | +#input {$var :function option=value} |
| 205 | +Hello {$var} |
| 206 | +
|
| 207 | +#input {$var :function option=value} |
| 208 | +#local $foo = {$bar :function option=value} |
| 209 | +Hello {$var}, you have a {$foo} |
| 210 | +
|
| 211 | +#match {$foo} {$bar} |
| 212 | +#when{foo bar} Hello {$foo} you have a {$var} |
| 213 | +#when{ * *} {$foo} hello you have a {$var} |
| 214 | +
|
| 215 | +#match {$foo :function option=value} {$bar :function option=value} |
| 216 | +#when {a b} {{ {$foo} is {$bar} }} |
| 217 | +#when {x y} {||} {$foo} is {$bar} {||} |
| 218 | +#when {* *} {| |}{$foo} is {$bar}{| |} |
| 219 | +
|
| 220 | +#input {$var :function option=value}#local $foo = {$bar :function option=value}Hello {$var}, you have a {$foo} |
| 221 | +
|
| 222 | +#match {$foo} {$bar}#when{foo bar} Hello {$foo} you have a {$var}#when{* *} {$foo} hello you have a {$var} |
| 223 | +
|
| 224 | +#match {$foo :function option=value} {$bar :function option=value}#when{a b}{{ {$foo} is {$bar} }} #when{x y}{||} {$foo} is {$bar} {||}#when{* *}{| |}{$foo} is {$bar}{| |} |
| 225 | +``` |
| 226 | + |
| 227 | +## 4. Reducing keywords |
| 228 | + |
| 229 | +Avoids keywords in favor of sigil based parsing. |
| 230 | +The theory here is that the syntactic sugar of `match` and `when` are nice the first time you use them |
| 231 | +but the benefit is lost or reduced after that. |
| 232 | + |
| 233 | +Uses double or paired sigils to reduce the need for escaping common characters (such as `?`) |
| 234 | + |
| 235 | +Requires escaping `#` in a pattern. |
| 236 | +Requires escaping `??` at the start of a pattern. |
| 237 | +Requires escaping `::[` in a pattern. |
| 238 | + |
| 239 | +``` |
| 240 | +#{$var :function option=value} |
| 241 | +Hello {$var} |
| 242 | +
|
| 243 | +#{$var :function option=value} |
| 244 | +#$foo = {$bar :function option=value} |
| 245 | +Hello {$var}, you have a {$foo} |
| 246 | +
|
| 247 | +?? {$foo} {$bar} |
| 248 | +::[ foo bar] Hello {$foo} you have a {$var} |
| 249 | +::[ * *] {$foo} hello you have a {$var} |
| 250 | +
|
| 251 | +?? {$foo :function option=value} {$bar :function option=value} |
| 252 | +::[a b] {{ {$foo} is {$bar} }} |
| 253 | +::[x y] {{ {$foo} is {$bar} }} |
| 254 | +::[* *] {| |}{$foo} is {$bar}{| |} |
| 255 | +
|
| 256 | +#{$var :function option=value}#$foo = {$bar :function option=value}Hello {$var}, you have a {$foo} |
| 257 | +
|
| 258 | +??{$foo}{$bar}::[foo bar] Hello {$foo} you have a {$var}::[* *] {$foo} hello you have a {$var} |
| 259 | +
|
| 260 | +??{$foo :function option=value}{$bar :function option=value}::[a b] { {$foo} is {$bar} }::[x y] { {$foo} is {$bar} }::[* *] {| |}{$foo} is {$bar}{| |} |
| 261 | +``` |
| 262 | + |
| 263 | +## 5. Use "blocks" for declarations and body |
| 264 | + |
| 265 | +Use code-mode "blocks" to introduce code. _(This section has an additional example)_ |
| 266 | + |
| 267 | +The theory here is that a "declarations block" would be a natural add-on and it doesn't |
| 268 | +require additional typing for each declaration. |
| 269 | + |
| 270 | +Note too that this syntax could be extended to allow other types of blocks, |
| 271 | +such as comments or different types of statement. |
| 272 | + |
| 273 | +Requires escaping `[` when used as a pattern character in an unquoted pattern. |
| 274 | + |
| 275 | +``` |
| 276 | +{# |
| 277 | + input {$var :function option=value} |
| 278 | +} |
| 279 | +Hello {$var} |
| 280 | +
|
| 281 | +// might be more natural as: |
| 282 | +{#input {$var :function option=value}} |
| 283 | +Hello {$var} |
| 284 | +
|
| 285 | +{# |
| 286 | + input {$var :function option=value} |
| 287 | + local $foo = {$bar :function option=value} |
| 288 | +} |
| 289 | +Hello {$var}, you have a {$foo} |
| 290 | +
|
| 291 | +{# |
| 292 | + match {$foo} {$bar} |
| 293 | + [ foo bar] Hello {$foo} you have a {$var} |
| 294 | + [ * *] {$foo} hello you have a {$var} |
| 295 | +} |
| 296 | +
|
| 297 | +{# |
| 298 | + input $foo :function option=value |
| 299 | +}{ |
| 300 | + match {$foo :function option=value} {$bar :function option=value} |
| 301 | + [a b] {{ {$foo} is {$bar} }} |
| 302 | + [x y] {{ {$foo} is {$bar} }} |
| 303 | + [* *] {| |}{$foo} is {$bar}{| |} |
| 304 | +} |
| 305 | +
|
| 306 | +{#input {$var :function option=value}}Hello {$var} |
| 307 | +
|
| 308 | +{#input {$var :function option=value} local $foo = {$bar :function option=value}}Hello {$var}, you have a {$foo} |
| 309 | +
|
| 310 | +{#match {$foo} {$bar}[foo bar] Hello {$foo} you have a {$var}[* *] {$foo} hello you have a {$var}} |
| 311 | +
|
| 312 | +{#input {$foo :function option=value}match {$foo :function option=value} {$bar :function option=value}[a b] {{ {$foo} is {$bar} }}[x y] {{ {$foo} is {$bar} }}[* *] {| |}{$foo} is {$bar}{| |}} |
| 313 | +``` |
| 314 | + |
| 315 | +## 5a. Declaration block but sigils for selectors |
| 316 | + |
| 317 | +Start in text mode. |
| 318 | +Enclose declarations in a block. |
| 319 | +Use a sigil for `match` selector. |
| 320 | + |
| 321 | +Requires escaping `[` when used as a pattern character, |
| 322 | +and the sequence `#match` when used at the start of a pattern. |
| 323 | + |
| 324 | +``` |
| 325 | +{# input $var :function option=value} |
| 326 | +Hello {$var} |
| 327 | +
|
| 328 | +{# input $var :function option=value |
| 329 | + local $foo = {$bar :function option=value} |
| 330 | +} |
| 331 | +Hello {$var}, you have a {$foo} |
| 332 | +
|
| 333 | +#match {$foo :function option=value} {$bar :function option=value} |
| 334 | +[a b] {$foo} is {$bar} |
| 335 | +[x y] {$foo} is {$bar} |
| 336 | +[* *] {$foo} is {$bar} |
| 337 | +
|
| 338 | +{#input $foo :function option=value |
| 339 | +local $baz = {|some annotation|}} |
| 340 | +#match {$foo} {$bar :function} |
| 341 | +[a b] {$foo} is {$bar} |
| 342 | +[x y] {$foo} is {$bar} |
| 343 | +[* *] {$foo} is {$bar} |
| 344 | +``` |
| 345 | + |
| 346 | +## 6. Use "statements" |
| 347 | + |
| 348 | +Many languages delimit statements using a terminator, such as `;`. |
| 349 | +In some languages, the terminator is the newline and lines can be extended using an escape like `\`. |
| 350 | +Here we use `;` as a terminator. |
| 351 | +Note that the closing `;` on `match` might be optional. |
| 352 | + |
| 353 | +Defining a statement syntax might allow us to introduce different types of selectors in future versions, |
| 354 | +such as looping constructs. |
| 355 | + |
| 356 | +Requires escaping the word `when` and the character `;` in a pattern, |
| 357 | +and the character `#` when used at the start of a pattern. |
| 358 | + |
| 359 | +``` |
| 360 | +#input {$var :function option=value}; |
| 361 | +Hello {$var} |
| 362 | +
|
| 363 | +#input {$var :function option=value}; |
| 364 | +#local $foo = {$bar :function option=value}; |
| 365 | +Hello {$var}, you have a {$foo} |
| 366 | +
|
| 367 | +#match {$foo} {$bar} |
| 368 | +when [ foo bar] Hello {$foo} you have a {$var} |
| 369 | +when [ * *] {$foo} hello you have a {$var} |
| 370 | +; |
| 371 | +
|
| 372 | +#match {$foo :function option=value} {$bar :function option=value} |
| 373 | + when [a b] { {$foo} is {$bar} } |
| 374 | + when [x y] { {$foo} is {$bar} } |
| 375 | + when [* *] {| |}{$foo} is {$bar}{| |} |
| 376 | +; |
| 377 | +
|
| 378 | +#input {$var :function option=value};#local $foo = {$bar :function option=value};Hello {$var}, you have a {$foo} |
| 379 | +
|
| 380 | +#match {$foo}{$bar}when [foo bar] Hello {$foo} you have a {$var}when [* *] {$foo} hello you have a {$var}; |
| 381 | +
|
| 382 | +#match {$foo :function option=value}{$bar :function option=value}when [a b] { {$foo} is {$bar} }when[x y] { {$foo} is {$bar} }when[* *] {| |}{$foo} is {$bar}{| |}; |
| 383 | +
|
| 384 | +``` |
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