603dafbaf7
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>
61 lines
2.3 KiB
C++
61 lines
2.3 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include "kernel/expr.h"
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#include "library/expr_lt.h"
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namespace lean {
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bool is_lt(expr const & a, expr const & b, bool use_hash) {
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if (is_eqp(a, b)) return false;
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unsigned da = get_depth(a);
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unsigned db = get_depth(b);
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if (da < db) return true;
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if (da > db) return false;
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if (a.kind() != b.kind()) return a.kind() < b.kind();
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if (use_hash) {
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if (a.hash() < b.hash()) return true;
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if (a.hash() > b.hash()) return false;
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}
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if (a == b) return false;
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switch (a.kind()) {
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case expr_kind::Var:
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return var_idx(a) < var_idx(b);
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case expr_kind::Constant:
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if (const_name(a) != const_name(b))
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return const_name(a) < const_name(b);
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else
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return is_lt(const_levels(a), const_levels(b), use_hash);
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case expr_kind::App:
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if (app_fn(a) != app_fn(b))
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return is_lt(app_fn(a), app_fn(b), use_hash);
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else
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return is_lt(app_arg(a), app_arg(b), use_hash);
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case expr_kind::Lambda: case expr_kind::Pi:
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if (binding_domain(a) != binding_domain(b))
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return is_lt(binding_domain(a), binding_domain(b), use_hash);
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else
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return is_lt(binding_body(a), binding_body(b), use_hash);
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case expr_kind::Sort:
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return is_lt(sort_level(a), sort_level(b), use_hash);
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case expr_kind::Local: case expr_kind::Meta:
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if (mlocal_name(a) != mlocal_name(b))
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return mlocal_name(a) < mlocal_name(b);
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else
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return is_lt(mlocal_type(a), mlocal_type(b), use_hash);
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case expr_kind::Macro:
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if (macro_def(a) != macro_def(b))
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return macro_def(a) < macro_def(b);
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if (macro_num_args(a) != macro_num_args(b))
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return macro_num_args(a) < macro_num_args(b);
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for (unsigned i = 0; i < macro_num_args(a); i++) {
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if (macro_arg(a, i) != macro_arg(b, i))
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return is_lt(macro_arg(a, i), macro_arg(b, i), use_hash);
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}
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return false;
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}
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lean_unreachable(); // LCOV_EXCL_LINE
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}
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}
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