Full changelog for Tact v1.5.0: https://github.com/tact-lang/tact/blob/main/CHANGELOG.md#150---2024-09-15

New Tact features

• asm functions: asm fun keccak256(s: Slice): Int { 1 INT HASHEXT_KECCAK256 };
• Wider range of serialization options for integers — uint1 through uint256 and int1 through int257: counter: Int as uint48;
• Allow omitting last semicolons in contract/trait declarations and definitions: trait Test { abstract fun foo() } -- the semicolon after foo() is not required anymore.

New builtin and stdlib functions and methods

• The exists method for the Map type: m.exists(key), equivalent to m.get(key) != null;
• The deepEquals method for the Map type: m1.deepEquals(m2);
• The toSlice method for structs and messages: struct.toSlice();
• The storeBit method for Builder type and the loadBit method for Slice type (aliases for storeBool and loadBool respectively): b.storeBit(true), sl.loadBit();
• slice, rawSlice, ascii and crc32 built-in functions;
• Corresponding stdlib functions for the new TVM instructions from 2023.07 and 2024.04 upgrades: storeBuilder extension function and gasConsumed, getComputeFee, getStorageFee, getForwardFee, getSimpleComputeFee, getSimpleForwardFee, getOriginalFwdFee, myStorageDue functions.
• Builder.storeMaybeRef, parseStdAddress and parseVarAddress stdlib functions.