This was trickier than expected as the expression parser, and in particular the bin-op parser will interpret negative patterns as a continuation of a binary operation and eventually choke on the next right-arrow symbol. This is due to how we actually completely erase newlines once we're done with the lexer. The newline separating when clause is actually semantically important. In principle, we could only parse an expression until the next newline.
Ideally, we would keep that newline in the list of token but it's difficult to figure out which newline to keep between two right arrows since a clause guard can be written over multiple lines. Though, since we know that this is only truly a problem for negative integers, we can use the same trick as for tuples and define a new 'NewLineMinus' token. That token CANNOT be part of a binop expression. That means it's impossible to write a binary operation with a minus over multiple lines, or more specifically, with the '-' symbol on a newline. This sounds like a fair limitation. What we get in exchange is less ambiguity when parsing patterns following expressions in when clause cases.
Another more cumbersome option could be to preserve the first newline encountered after a 'right-arrow' symbol and before any parenthesis or curly brace is found (which would otherwise signal the beginning of a new block). That requires to traverse, at least partially, the list of tokens twice. This feels unnecessary for now and until we do face a similar issue with a binary operator.
Rules are now as follows:
- If a pipeline contains a newline, then the entire pipeline is formatted over multiple lines.
- If it doesn't, then it's formatted as a single-line UNLESS it cannot fit; in which case, we fallback to multiline again.
The core observation is that **in the context of Aiken** (i.e. on-chain logic)
people do not generally want to use String. Instead, they want
bytearrays.
So, it should be easy to produce bytearrays when needed and it should
be the default. Before this commit, `"foo"` would parse as a `String`.
Now, it parses as a `ByteArray`, whose bytes are the UTF-8 bytes
encoding of "foo".
Now, to make this change really "fool-proof", we now want to:
- [ ] Emit a parse error if we parse a UTF-8 bytearray literal in
place where we would expect a `String`. For example, `trace`,
`error` and `todo` can only be followed by a `String`.
So when we see something like:
```
trace "foo"
```
we know it's a mistake and we can suggest users to use:
```
trace @"foo"
```
instead.
- [ ] Emit a warning if we ever see a bytearray literals UTF-8, which
is either 56 or 64 character long and is a valid hexadecimal string.
For example:
```
let policy_id = "29d222ce763455e3d7a09a665ce554f00ac89d2e99a1a83d267170c6"
```
This is _most certainly_ a mistake, as this generates a ByteArray of
56 bytes, which is effectively the hex-encoding of the provided string.
In this scenario, we want to warn the user and inform them they probably meant to use:
```
let policy_id = #"29d222ce763455e3d7a09a665ce554f00ac89d2e99a1a83d267170c6"
```
Interestingly enough, chumsky seems to fail when given a 'choice' with
more than 25 elements. That's why this commit groups together some of
the choices as another nested 'choice'.
This changes allow to use parenthesis `(` `)` to encapsulate
expressions in addition to braces `{` `}` used to define blocks.
The main use-case is for arithmetic and boolean expressions for which
developers are used to using parenthesis. For example:
```
{ 14 + 42 } * 1337
```
can now be written as:
```
( 14 + 42 ) * 1337
```
This may sound straightforward at first but wasn't necessarily trivial
in Aiken given that (a) everything is an expression, (b) whitespaces
do not generally matter and (c) there's no symbol indicating the end
of a 'statement' (because there's no statement).
Thus, we have to properly disambiguate between:
```
let foo = bar(14 + 42)
```
and
```
let foo = bar
(14 + 42)
```
Before this commit, the latter would be interpreted as a function call
and would lead to a somewhat puzzling error. Now, the newline serves
as a delimiting symbol. The trade-off being that for a function call,
the left parenthesis has to be on the same line as the function name
identifier -- which is a fair trade off. So this is still allowed:
```
let foo = bar(
14 + 42
)
```
As there's very little ambiguity about it.
This fixes#236 and would seemingly allow us to get rid of the leading
`#` in front of tuples.
rvcas