@kha The runtime folder includes what is needed to link a
standalone Lean program. It is still contains some unnecessary files.
We will be able to remove them after we release Lean4.
This field was originally added to create hashtables based on pointer
equality. We don't use them anymore, and the caches based on
m_hash_alloc can be implemented using m_hash without any performance
impact. This commit also fixes two places where `expr_set` was used
instead of `expr_struct_set`.
This commit is also important for the Lean4 plans where `expr` will
be implemented in Lean, and fields like `m_hash_alloc` would require us
to track state.
We simulate it in the following way:
1- An opaque 'let'-expressions (let x : t := v in b) is encoded as
((fun (x : t), b) v)
We also use a macro (let-macro) to mark this pattern.
Thus, the pretty-printer knows how to display it correctly.
2- Transparent 'let'-expressions are eagerly expanded by the parser.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Before this commit, we "stored" macro arguments using applications.
This representation had some issues. Suppose we use [m a] to denote a macro
application. In the old representation, ([m a] b) and [m a b] would have
the same representation. Another problem is that some procedures (e.g., type inference)
would not have a clean implementation.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
