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https://github.com/ton-blockchain/ton
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f3e620f48c
This commit introduces nullable types `T?` that are distinct from non-nullable `T`. Example: `int?` (int or null) and `int` are different now. Previously, `null` could be assigned to any primitive type. Now, it can be assigned only to `T?`. A non-null assertion operator `!` was also introduced, similar to `!` in TypeScript and `!!` in Kotlin. If `int?` still occupies 1 stack slot, `(int,int)?` and other nullable tensors occupy N+1 slots, the last for "null precedence". `v == null` actually compares that slot. Assigning `(int,int)` to `(int,int)?` implicitly creates a null presence slot. Assigning `null` to `(int,int)?` widens this null value to 3 slots. This is called "type transitioning". All stdlib functions prototypes have been updated to reflect whether they return/accept a nullable or a strict value. This commit also contains refactoring from `const FunctionData*` to `FunctionPtr` and similar.
39 lines
1 KiB
Text
39 lines
1 KiB
Text
// A part of standard library for Tolk
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tolk 0.8
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/**
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Lisp-style lists are nested 2-elements tuples: `(1, (2, (3, null)))` represents list `[1, 2, 3]`.
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Elements of a list can be of different types.
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Empty list is conventionally represented as TVM `null` value.
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*/
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@pure
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fun createEmptyList(): tuple
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asm "PUSHNULL";
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/// Adds an element to the beginning of lisp-style list.
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/// Note, that it does not mutate the list: instead, it returns a new one (it's a lisp pattern).
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@pure
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fun listPrepend<X>(head: X, tail: tuple?): tuple
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asm "CONS";
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/// Extracts the head and the tail of lisp-style list.
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@pure
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fun listSplit<X>(list: tuple): (X, tuple?)
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asm "UNCONS";
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/// Extracts the tail and the head of lisp-style list.
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/// After extracting the last element, tuple is assigned to null.
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@pure
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fun listNext<X>(mutate self: tuple?): X
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asm( -> 1 0) "UNCONS";
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/// Returns the head of lisp-style list.
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@pure
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fun listGetHead<X>(list: tuple): X
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asm "CAR";
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/// Returns the tail of lisp-style list.
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@pure
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fun listGetTail(list: tuple): tuple?
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asm "CDR";
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