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I'm working on a language that embeds Javascript. Javascript syntax makes it quite easy to find the end of a complete block by considering just parens, brackets

by tlb 8y ago

I'm working on a language that embeds Javascript. Javascript syntax makes it quite easy to find the end of a complete block by considering just parens, brackets, braces, strings, and comments. Then I can just pass the string to a JS interpreter. So it's easy to allow javascript { ...any valid javascript code... } C++ syntax, on the other hand, makes it very hard to delimit a block. For instance, it's hard to guess whether a > is an operator or the end of a template parameter list. And preprocessor macros mean that the entire context of all the includes files before the current point can change what any token means. I think a good goal for a syntax is to make it easy to delimit blocks without a complete parser. It also makes syntax highlighting practical.

austincheney 8y ago
JavaScript related languages introduce the same problem. Is the `<` a comparison operator, the start of a type generics segment from something like TypeScript, a markup tag from something like React, or something else? JavaScript alone does not provide the context for that clarity. Boost templates in C++ are similar sort of problem, but there is less variability around boost templates, so they would be easier to discern from the surrounding syntax than the several JavaScript variances. > I think a good goal for a syntax is to... I manage a parser supporting many languages, not a language. I don't have the freedom to dictate what a language should look like. Instead my application must have the flexibility to tolerate other peoples' language design decisions, what ever they may be.
a1369209993 8y ago
I've discovered that python-style block syntax makes it trivial to embed arbitrary other languages, eg: while lang == nothing: lang = something() interpret(lang,:: ... whatever )) }] --] </script> __END__ {{({[(( /* ... ) # works fine

by tlb 8y ago

austincheney 8y ago

JavaScript related languages introduce the same problem. Is the `<` a comparison operator, the start of a type generics segment from something like TypeScript, a markup tag from something like React, or something else? JavaScript alone does not provide the context for that clarity. Boost templates in C++ are similar sort of problem, but there is less variability around boost templates, so they would be easier to discern from the surrounding syntax than the several JavaScript variances. > I think a good goal for a syntax is to... I manage a parser supporting many languages, not a language. I don't have the freedom to dictate what a language should look like. Instead my application must have the flexibility to tolerate other peoples' language design decisions, what ever they may be.

a1369209993 8y ago

I've discovered that python-style block syntax makes it trivial to embed arbitrary other languages, eg: while lang == nothing: lang = something() interpret(lang,:: ... whatever )) }] --] </script> __END__ {{({[(( /* ... ) # works fine