Since we do not have tuple in this version of Leo, we cannot have expression
statements, because normally expressions used as statements would have to return
the empty tuple, since we disallow throwing away values in Leo.
Since this pre-testnet3 version of Leo does not support tuple types, and since a
missing function type is meant to be interpreted as the empty tuple type `()` in
future versions of Leo, it seems appropriate to require a function output type
in this version of Leo. We could instead default to a different type
(e.g. bool), but it seems cleaner to require it for now, and make it optional
later.
This mirrors, in pre-testnet3, the change in PR #1699 in testnet3.
Since in pre-testnet3 we have fewer kinds expressions, the category of postfix
expressions disappears altogether with this re-classification.
This does not change the language. It only renames two related rule names:
function-input => named-parameter
function-inputs => named-parameters
According to the new nomenclature, there are function parameters, which are self
parameters and named parameters: the nomenclature is clear and "symmetric".
The problem with the previous nomenclature is that both self and named
parameters are inputs, not just the named ones.
These are needed to make parsing unambiguous. They require the test of a
conditional statement and the ending bound of a loop statement to not be or
start with a circuit expression.
This is obtained by removing features from the grammar currently in the testnet3
branch.
The documentation comments have been removed to keep the file smaller and
simpler to read, as readers of this file should be already familiar with Leo.
Furthermore, that documentation material is being moved to the Leo Language
Reference.
This commit also folds the format string grammar (for console print strings)
into (a separate section of) the same file, again for simplicity. The previous
separate small file (and generated markdown) for format strings has thus been
removed.
