Add parse_let
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura
parent
7a9319b72e
commit
afd62ced87
7 changed files with 68 additions and 2 deletions
15
examples/ex4.lean
Normal file
15
examples/ex4.lean
Normal file
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@ -0,0 +1,15 @@
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Show (fun x : Bool, (fun y : Bool, x /\ y))
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Show let x := true,
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y := true
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in (let z := x /\ y,
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f := (fun arg1 arg2 : Bool, arg1 /\ arg2 <=>
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arg2 /\ arg1 <=>
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arg1 \/ arg2 \/ arg2)
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in (f x y) \/ z)
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Eval let x := true,
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y := true,
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z := x /\ y,
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f := (fun arg1 arg2 : Bool, arg1 /\ arg2 <=>
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arg2 /\ arg1 <=>
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arg1 \/ arg2 \/ arg2)
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in (f x y) \/ z
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@ -21,5 +21,7 @@ void init_builtin_notation(frontend & f) {
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f.add_infixr("\u2228", 30, const_name(mk_or_fn()));
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f.add_infixr("=>", 25, const_name(mk_implies_fn()));
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f.add_infixr("\u21D2", 25, const_name(mk_implies_fn()));
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f.add_infixr("<=>", 25, const_name(mk_iff_fn()));
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f.add_infixr("\u21D4", 25, const_name(mk_iff_fn()));
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}
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}
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@ -13,9 +13,10 @@ Author: Leonardo de Moura
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#include "type_check.h"
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#include "free_vars.h"
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#include "builtin_notation.h"
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#include "pp.h"
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#include "builtin.h"
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#include "arith.h"
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#include "pp.h"
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#include "printer.h"
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namespace lean {
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static name g_definition_kwd("Definition");
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@ -81,6 +82,8 @@ struct parser_fn {
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bool curr_is_identifier() const { return curr() == scanner::token::Id; }
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bool curr_is_lparen() const { return curr() == scanner::token::LeftParen; }
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bool curr_is_colon() const { return curr() == scanner::token::Colon; }
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bool curr_is_comma() const { return curr() == scanner::token::Comma; }
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bool curr_is_in() const { return curr() == scanner::token::In; }
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void check_identifier(char const * msg) { if (!curr_is_identifier()) throw parser_error(msg); }
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name check_identifier_next(char const * msg) { check_identifier(msg); name r = curr_name(); next(); return r; }
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@ -348,6 +351,31 @@ struct parser_fn {
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return parse_abstraction(false);
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}
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expr parse_let() {
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next();
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local_decls::mk_scope scope(m_local_decls);
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buffer<std::pair<name, expr>> bindings;
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while (true) {
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name id = check_identifier_next("invalid let expression, identifier expected");
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check_assign_next("invalid let expression, ':=' expected");
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expr val = parse_expr();
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register_binding(id);
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bindings.push_back(mk_pair(id, val));
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if (curr_is_in()) {
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next();
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expr r = parse_expr();
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unsigned i = bindings.size();
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while (i > 0) {
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--i;
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r = mk_let(bindings[i].first, bindings[i].second, r);
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}
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return r;
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} else {
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check_comma_next("invalid let expression, ',' or 'in' expected");
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}
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}
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}
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expr parse_int() {
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expr r = mk_int_value(m_scanner.get_num_val().get_numerator());
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next();
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@ -374,6 +402,7 @@ struct parser_fn {
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case scanner::token::LeftParen: return parse_lparen();
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case scanner::token::Lambda: return parse_lambda();
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case scanner::token::Pi: return parse_pi();
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case scanner::token::Let: return parse_let();
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case scanner::token::IntVal: return parse_int();
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case scanner::token::DecimalVal: return parse_decimal();
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case scanner::token::StringVal: return parse_string();
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@ -19,6 +19,8 @@ static name g_arrow_unicode("\u2192");
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static name g_lambda_name("fun");
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static name g_type_name("Type");
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static name g_pi_name("Pi");
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static name g_let_name("let");
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static name g_in_name("in");
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static name g_arrow_name("->");
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static name g_eq_name("=");
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@ -193,6 +195,10 @@ scanner::token scanner::read_a_symbol() {
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return token::Pi;
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else if (m_name_val == g_type_name)
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return token::Type;
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else if (m_name_val == g_let_name)
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return token::Let;
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else if (m_name_val == g_in_name)
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return token::In;
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else
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return is_command(m_name_val) ? token::CommandId : token::Id;
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}
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@ -347,6 +353,8 @@ std::ostream & operator<<(std::ostream & out, scanner::token const & t) {
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case scanner::token::Lambda: out << g_lambda_unicode; break;
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case scanner::token::Pi: out << g_pi_unicode; break;
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case scanner::token::Arrow: out << g_arrow_unicode; break;
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case scanner::token::Let: out << "let"; break;
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case scanner::token::In: out << "in"; break;
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case scanner::token::Id: out << "Id"; break;
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case scanner::token::CommandId: out << "CId"; break;
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case scanner::token::IntVal: out << "Int"; break;
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@ -19,7 +19,7 @@ class scanner {
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public:
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enum class token {
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LeftParen, RightParen, LeftCurlyBracket, RightCurlyBracket, Colon, Comma, Period, Lambda, Pi, Arrow,
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Id, CommandId, IntVal, DecimalVal, StringVal, Eq, Assign, Type, Eof
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Let, In, Id, CommandId, IntVal, DecimalVal, StringVal, Eq, Assign, Type, Eof
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};
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protected:
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int m_spos; // position in the current line of the stream
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@ -167,6 +167,7 @@ MK_BUILTIN(ite_fn, ite_fn_value);
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MK_CONSTANT(if_fn, name("if"));
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MK_CONSTANT(implies_fn, name("implies"));
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MK_CONSTANT(iff_fn, name("iff"));
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MK_CONSTANT(and_fn, name("and"));
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MK_CONSTANT(or_fn, name("or"));
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MK_CONSTANT(not_fn, name("not"));
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@ -210,6 +211,9 @@ void add_basic_theory(environment & env) {
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// implies(x, y) := ite x y True
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env.add_definition(implies_fn_name, p2, Fun({{x, Bool}, {y, Bool}}, bIf(x, y, True)));
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// iff(x, y) := x = y
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env.add_definition(iff_fn_name, p2, Fun({{x, Bool}, {y, Bool}}, Eq(x, y)));
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// not(x) := ite x False True
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env.add_definition(not_fn_name, p1, Fun({x, Bool}, bIf(x, False, True)));
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@ -67,6 +67,14 @@ inline expr mk_implies(unsigned num_args, expr const * args) { lean_assert(num_a
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inline expr Implies(expr const & e1, expr const & e2) { return mk_implies(e1, e2); }
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inline expr Implies(std::initializer_list<expr> const & l) { return mk_implies(l.size(), l.begin()); }
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/** \brief Return the Lean Iff operator */
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expr mk_iff_fn();
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/** \brief Return (e1 iff e2) */
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inline expr mk_iff(expr const & e1, expr const & e2) { return mk_app(mk_iff_fn(), e1, e2); }
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inline expr mk_iff(unsigned num_args, expr const * args) { return mk_bin_rop(mk_iff_fn(), True, num_args, args); }
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inline expr Iff(expr const & e1, expr const & e2) { return mk_iff(e1, e2); }
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inline expr Iff(std::initializer_list<expr> const & l) { return mk_iff(l.size(), l.begin()); }
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/** \brief Return the Lean And operator */
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expr mk_and_fn();
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/** \brief Return (e1 and e2) */
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