Dear Bitcoin devs, I am the author of OCaml-bitcoin , a library offering an OCaml interface to the official Bitcoin client API. For those who may be unfamiliar with it, OCaml is one of those functional programming languages with a very rich and expressive type system . Given its emphasis on safety, its industrial users are disproportionally found in the aerospace and financial sectors.
Now, OCaml programmers care a lot about types, because experience has taught them that deep down most programming errors are just type errors. From this stems my request: please consider defining more precisely the type information associated with each API call in the JSON-RPC reference . To give you a better idea of what I'm talking about, please take a look at the API offered by OCaml-bitcoin , and the associated type definitions  (note that these have not been updated for Bitcoin Core 0.10 yet). I've created the type definitions from information gathered from the Bitcoin wiki and from looking at the Bitcoin Core source-code. I wouldn't be surprised if it contains errors, because neither the source-code nor the wiki is very precise about the actual types being used. As an example, consider type hexspk_t ("hex representation of script public key"). Is this really the same type used in both signrawtransaction and createmultisig? Improving this situation would pose a minimal burden on bitcoin devs: all that would be required is defining the precise set of types used in the RPC API, and annotating the RPC calls either in the source-code itself or in the API reference documentation. It would make writing bindings such as mine far easier and less error prone, and it would have the added advantage of better documenting the Bitcoin Core source-code itself. Also, note that it is not necessary to extend this request to the deep data structures returned by some API calls. Consider for instance the gettransaction function of the OCaml-bitcoin API: it returns the raw JSON object without any attempt to process it. This is because that's a fairly niche facility, and the bindings would balloon in size if I were to process every single large return object. Instead, the bindings take the more pragmatic stance of only processing the parameters and return results where a strong type discipline is imperative. When I raised this issue on IRC a number of questions were posed. What follows is my attempt to answer them: Q: What does it matter, if JSON only has a tiny set of types? A: JSON being the serialisation format is irrelevant. The client bindings know that even if a public ECDSA key is serialised as a string, it does not stop being a public ECDSA key, and should only be used where a public ECDSA key is expected. Q: What does it matter if the types are not even distinguished in the C++ source of Bitcoin Core? A: That is unfortunate, because it opens the door to bugs caused by type errors. Moreover, even if the C++ source is "stringly-typed" and does not enforce a strong type discipline, that does not mean that the types are not there. Even if a public and private key are both represented as strings, can you use one where the other is expected? If not, then they actually have different types! Q: Isn't this a maintenance nightmare, given the changes to Bitcoin core? A: Actually, the most burdensome part is what motivated this message: keeping track of the types used. If the Bitcoin API reference were more precise, keeping the bindings up-to-date would be trivial and even mechanical, because the API is now fairly stable. Thank you very much for your attention, and for all the work you guys put into Bitcoin development. It is much appreciated and not acknowledged often enough! Best regards, Dario Teixeira  https://github.com/darioteixeira/ocaml-bitcoin  http://ocaml.org/learn/description.html  https://bitcoin.org/en/developer-reference#bitcoin-core-apis  http://ocaml-bitcoin.forge.ocamlcore.org/apidoc/Bitcoin.ENGINE.html  http://ocaml-bitcoin.forge.ocamlcore.org/apidoc/Bitcoin.html ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=190641631&iu=/4140/ostg.clktrk _______________________________________________ Bitcoin-development mailing list Bitcoinfirstname.lastname@example.org https://lists.sourceforge.net/lists/listinfo/bitcoin-development