FunC Update 2022.05

We are glad to present you new features of the FunC programming language:

Compiler directives

Those are keywords that start with # and instruct compiler to do some actions, checks or adjust parameters.

Introducing the first derivatives - #pragma and #include.

Documentation

#pragma version;

Used to enforce specific version of FunC compiler when compiling the file.

Version is specified in semver format, that is a.b.c, where a is major version, b is minor, and c is patch.

Comparison operators =, >, <, >=, <=, ^ can be used.

Documentation

#include "filename.fc";

The #include directive allows to include another FunC source code file that will be parsed at the place of include.

Documentation

String literals

Strings in FunC are quoted in double quotes " like "this is a string". Special symbols like \n and multi-line strings are not supported. Optionally string literals may specify type after them such as "string"u.

The following strings types are supported:

• without type - used for asm function definitions and to define a slice const by ASCII string,
• s - defines a raw slice const by its contents (hex-encoded and optionally bit-padded),
• a - creates a slice const containing MsgAddressInt structure from specified address,
• u - creates an int const that corresponds to hex values of provided ASCII string,
• h - creates an int const that is first 32 bits of SHA256 hash of the string,
• H - creates an int const that is all 256 bits of SHA256 hash of the string,
• c - creates an int const that is crc32 value of the string.

For example, following values result in the corresponding consts:

• "string" becomes x{737472696e67} slice const,
• "abcdef"s becomes x{abcdef} slice const,
• "Ef8zMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzMzM0vF"a becomes x{9FE6666666666666666666666666666666666666666666666666666666666666667_} slice const (addr_std$10 anycast:none$0 workchain_id:int8=0xFF address:bits256=0x33...33),
• "NstK"u becomes 0x4e73744b int const,
• "transfer(slice, int)"h becomes 0x7a62e8a8 int const,
• "transfer(slice, int)"H becomes 0x7a62e8a8ebac41bd6de16c65e7be363bc2d2cbc6a0873778dead4795c13db979 int const,
• "transfer(slice, int)"c becomes 2235694568 int const.

Documentation

Constants

FunC allows to define compile-time constants that are substituted and precalculated during compilation.

Constants are defined as const optional-type identifier = value-or-expression;

optional-type can be used to force a specific type of constant and for better readability.

As of now int and slice types are supported.

value-or-expression can be a literal or a pre-computable expression of literals and constants.

For example, constants can be defined as following:

• const int101 = 101; defines int101 constant that is equivalent to numeric literal 101,
• const str1 = "const1", str2 = "aabbcc"s; defines two constants that are equal to their corresponding strings,
• const int int240 = ((int1 + int2) * 10) << 3; defines int240 constant that equals to the result of calculation,
• const slice str2r = str2; defines str2r constant that is equal to value of str2 constant.

Since numeric constants are substituted during compilation all optimization and pre-computations performed during compilation are successfully performed (unlike old method defining constants via inline asm PUSHINTs).

Documentation

To start using new features you need to use the func compiler from the master branch  https://github.com/ton-blockchain/ton.