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Really? It appears to be much more of a static analysis tool than a cross-compiled psuedo-syntax. Here's what it outputs: flow examples/01_HelloWorld/hello.

Really? It appears to be much more of a static analysis tool than a cross-compiled psuedo-syntax. Here's what it outputs: flow examples/01_HelloWorld/hello.js /hello.js:7:5,19: string This type is incompatible with hello.js:4:10,13: number Found 1 error

inglor 12y ago
EDIT: looks like it supports type annotations similar to closure compiler's (in docs) https://github.com/facebook/flow/blob/master/tests/docblock/docblock.js https://github.com/facebook/flow/blob/master/tests/docblock/... Try running an annotated file in the browser - it's simply not valid ECMAScript syntax and no JavaScript runtime will run it 'as is'. If the code requires transformation by a compiler aware of the language semantics and syntax - it's transpiling in my book. Just like TypeScript is a superset of ECMAScript - so is Flow (in a much lighter, closer to source sense it seems).
- masklinn 12y ago
  > Try running an annotated file in the browser - it's simply not valid ECMAScript syntax and no JavaScript runtime will run it 'as is'. Of course not, but the point was that it's not a different language, it simply adds type annotations. If you strip out the type annotations, it should be a valid JS file.
  - inglor 12y ago
    This is also true for TypeScript though. The only thing that's not directly JS in TypeScript is shims for new JS features (from ES6) not yet implemented.
    - masklinn 12y ago
      > This is also true for TypeScript though. AFAIK none of these are valid javascript, event assuming ES6: * class-level variables (resolved as instance variables) * field visibility * initializer constructors (constructor without a body automatically assigning to a field) * enum types That is, you can't remove type annotations (and `interface` declarations which can probably get a pass) and end up with valid JS, which seems to be what flow yields.
drderidder 12y ago
Ah, I see what you mean now with the type annotations. It looks like they require the jsx transpiler if you use them. Still, flow isn't doing the transcoding, just the static analysis part. I wish the type annotations could have been in the form of jsdoc-style comments though.

inglor 12y ago

EDIT: looks like it supports type annotations similar to closure compiler's (in docs) https://github.com/facebook/flow/blob/master/tests/docblock/docblock.js https://github.com/facebook/flow/blob/master/tests/docblock/... Try running an annotated file in the browser - it's simply not valid ECMAScript syntax and no JavaScript runtime will run it 'as is'. If the code requires transformation by a compiler aware of the language semantics and syntax - it's transpiling in my book. Just like TypeScript is a superset of ECMAScript - so is Flow (in a much lighter, closer to source sense it seems).

masklinn 12y ago
> Try running an annotated file in the browser - it's simply not valid ECMAScript syntax and no JavaScript runtime will run it 'as is'. Of course not, but the point was that it's not a different language, it simply adds type annotations. If you strip out the type annotations, it should be a valid JS file.
- inglor 12y ago
  This is also true for TypeScript though. The only thing that's not directly JS in TypeScript is shims for new JS features (from ES6) not yet implemented.
  - masklinn 12y ago
    > This is also true for TypeScript though. AFAIK none of these are valid javascript, event assuming ES6: * class-level variables (resolved as instance variables) * field visibility * initializer constructors (constructor without a body automatically assigning to a field) * enum types That is, you can't remove type annotations (and `interface` declarations which can probably get a pass) and end up with valid JS, which seems to be what flow yields.

drderidder 12y ago

Ah, I see what you mean now with the type annotations. It looks like they require the jsx transpiler if you use them. Still, flow isn't doing the transcoding, just the static analysis part. I wish the type annotations could have been in the form of jsdoc-style comments though.