Paul Cadman 9faa88d4da Add support for Strings in the Anoma backend (#2789) ... This PR adds support for the `String` type, String literals and string concatenation to the Nockma backend. Support for the builtins `show` and `intToString` is not supported. ### Example test079.juvix ``` module test079; import Stdlib.Prelude open; main (s : String) : String := s ++str " " ++str "✨ héllo" ++str " " ++str "world ✨"; ``` args.nockma ``` [quote "Juvix!"] ``` ``` $ juvix compile anoma test079.juvix $ juvix dev nockma run test079.pretty.nockma --args args.nockma "Juvix! ✨ héllo world ✨" ``` ### String representation A String is a sequence of UTF-8 encoded bytes. We interpret these bytes as a sequence of bits to represent the string as an integer atom in nockma. For example: The string `"a"` is UTF-8 encoded as `97` which is `0b1100001` in bits. The string `"ab"` is UTF-8 encoded at the pair of bytes: `97 98` which is `0b1100001 0b1100010`. When we combine the bytes into a single sequence of bits we must take care to pad each binary representation with zeros to each byte boundary. So the binary representation of `"ab"` as an atom is `0b110000101100010` or `24930` as an integer atom. ### String concatenation We use the [cat](ea25f88cea/hoon/anoma.hoon (L215)) function in the Anoma stdlib to concatenate the bytes representing two strings. We need to use the block parameter `3` in the Anoma call because we want to treat the atoms representing the strings as sequences of bytes (= 2^3 bits). To find the relevant Nock code to call `cat` with block parameter `3` we use the urbit dojo as follows: ``` => anoma !=(~(cat block 3)) [8 [9 10 0 7] 9 4 10 [6 7 [0 3] 1 3] 0 2] ``` ### Stdlib intercept in Evaluator The evaluator has support for strings using `AtomHint`s, so strings can be printed and traced. The stdlib `cat` call is also intercepted because evaluating the unjetted hoon version is slow. ### String support in pretty nockma In a pretty nockma file or `nock` quasi-quote you can write double quoted string literals, e.g "abc". These are automatically translated to UTF-8 integer atoms as in the previous section.		2024-05-28 17:20:19 +01:00
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Positive.hs	Add support for Strings in the Anoma backend (#2789)	2024-05-28 17:20:19 +01:00