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https://github.com/ton-blockchain/ton
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799e2d1265
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)
146 lines
2.8 KiB
Text
146 lines
2.8 KiB
Text
import "@stdlib/lisp-lists"
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@method_id(101)
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fun test1() {
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var numbers: tuple = createEmptyList();
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numbers = listPrepend(1, numbers);
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numbers = listPrepend(2, numbers);
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numbers = listPrepend(3, numbers);
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numbers = listPrepend(4, numbers);
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var (h: int, numbers redef) = listSplit(numbers);
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h += listGetHead(numbers);
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_ = null;
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(_, _) = (null, null);
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var t = createEmptyTuple();
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do {
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var num: int = numbers.listNext();
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t.tuplePush(num);
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} while (numbers != null);
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return (h, numbers == null, t);
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}
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@method_id(102)
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fun test2(x: int) {
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if (null != x) {
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var y: int = null;
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if (y != null) { return 10; }
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return y;
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}
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try {
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return x + 10; // will throw, since not a number
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} catch {
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return -1;
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}
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return 100;
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}
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fun myIsNull(x: int): int {
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return x == null ? -1 : x;
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}
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@method_id(103)
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fun test3(x: int) {
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return myIsNull(x > 10 ? null : x);
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}
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fun getUntypedNull() {
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var untyped: null = null;
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if (true) {
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return untyped;
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}
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return untyped;
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}
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@method_id(104)
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fun test4(): null {
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var (_, (_, untyped: null)) = (3, (createEmptyTuple, null));
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if (true) {
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return untyped;
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}
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return untyped;
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}
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@method_id(105)
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fun test5() {
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var n: slice = getUntypedNull();
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return !(null == n) ? n.loadInt(32) : 100;
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}
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@method_id(107)
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fun test7() {
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var b = beginCell().storeMaybeRef(null);
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var s = b.endCell().beginParse();
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var c = s.loadMaybeRef();
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return (null == c) * 10 + (b != null);
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}
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fun main() {
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// now, the compiler doesn't optimize this at compile-time, fif codegen contains ifs
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var i: int = null;
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if (i == null) {
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return 1;
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}
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return 10;
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}
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/**
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@testcase | 101 | | 7 -1 [ 3 2 1 ]
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@testcase | 102 | 5 | (null)
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@testcase | 102 | null | -1
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@testcase | 103 | 5 | 5
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@testcase | 103 | 15 | -1
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@testcase | 104 | | (null)
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@testcase | 105 | | 100
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@testcase | 107 | | -11
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@fif_codegen
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"""
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test1 PROC:<{
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//
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PUSHNULL // numbers
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1 PUSHINT // numbers _2=1
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SWAP // _2=1 numbers
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CONS // numbers
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2 PUSHINT // numbers _4=2
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SWAP // _4=2 numbers
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CONS // numbers
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3 PUSHINT // numbers _6=3
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SWAP // _6=3 numbers
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CONS // numbers
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4 PUSHINT // numbers _8=4
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SWAP // _8=4 numbers
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CONS // numbers
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UNCONS // h numbers
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DUP // h numbers numbers
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CAR // h numbers _12
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"""
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@fif_codegen
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"""
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main PROC:<{
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//
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PUSHNULL // i
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ISNULL // _2
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IFJMP:<{ //
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1 PUSHINT // _3=1
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}> //
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10 PUSHINT // _4=10
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}>
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"""
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@fif_codegen
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"""
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test7 PROC:<{
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...
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LDOPTREF // b _18 _17
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DROP // b c
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ISNULL // b _11
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10 MULCONST // b _13
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SWAP // _13 b
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ISNULL // _13 _14
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0 EQINT // _13 _15
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ADD // _16
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}>
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"""
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*/
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