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[Tolk] Rewrite the type system from Hindley-Milner to static typing

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FunC's (and Tolk's before this PR) type system is based on Hindley-Milner.
This is a common approach for functional languages, where
types are inferred from usage through unification.
As a result, type declarations are not necessary:
() f(a,b) { return a+b; } // a and b now int, since `+` (int, int)

While this approach works for now, problems arise with the introduction
of new types like bool, where `!x` must handle both int and bool.
It will also become incompatible with int32 and other strict integers.
This will clash with structure methods, struggle with proper generics,
and become entirely impractical for union types.

This PR completely rewrites the type system targeting the future.
1) type of any expression is inferred and never changed
2) this is available because dependent expressions already inferred
3) forall completely removed, generic functions introduced
   (they work like template functions actually, instantiated while inferring)
4) instantiation `<...>` syntax, example: `t.tupleAt<int>(0)`
5) `as` keyword, for example `t.tupleAt(0) as int`
6) methods binding is done along with type inferring, not before
   ("before", as worked previously, was always a wrong approach)
This commit is contained in:
tolk-vm 2024-12-30 22:31:27 +07:00
parent 3540424aa1
commit 799e2d1265
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GPG key ID: 7905DD7FE0324B12
101 changed files with 5402 additions and 2713 deletions
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13
tolk/lexer.h
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@ -125,9 +125,9 @@ enum TokenType {
tok_builder,
tok_continuation,
tok_tuple,
tok_auto,
tok_void,
tok_arrow,
tok_as,
tok_tolk,
tok_semver,
@ -166,6 +166,12 @@ class Lexer {
public:
struct SavedPositionForLookahead {
const char* p_next = nullptr;
int cur_token_idx = 0;
Token cur_token;
};
explicit Lexer(const SrcFile* file);
Lexer(const Lexer&) = delete;
Lexer &operator=(const Lexer&) = delete;
@ -209,6 +215,9 @@ public:
void next();
void next_special(TokenType parse_next_as, const char* str_expected);
SavedPositionForLookahead save_parsing_position() const;
void restore_position(SavedPositionForLookahead saved);
void check(TokenType next_tok, const char* str_expected) const {
if (cur_token.type != next_tok) {
unexpected(str_expected); // unlikely path, not inlined
@ -230,6 +239,6 @@ public:
void lexer_init();
// todo #ifdef TOLK_PROFILING
void lexer_measure_performance(const AllSrcFiles& files_to_just_parse);
void lexer_measure_performance(const AllRegisteredSrcFiles& files_to_just_parse);
} // namespace tolk