| Feature | 7 |Solidity | 8 |Vyper | 9 |
|---|---|---|
| Version | 12 |
13 | $ solc --version 14 | Version: 0.7.015 | |
16 |
17 | $ vyper --version 18 | 0.2.419 | |
20 |
| General notes on syntax | 23 |
24 | Solidity loosely borrows its syntax from Javascript and C 25 | |
26 |
27 | Vyper syntax is valid Python 3 syntax (but the opposite is not true) 28 | |
29 |
| Block delimiters | 32 |
33 | { }
34 | |
35 |
36 | : # Vyper uses Python's off-side rule37 | |
38 |
| Statement separator | 41 |
42 | ;43 | |
44 |
45 | '\n' and :46 | |
47 |
| End of line comment | 50 |
51 | // comment52 | |
53 |
54 | # comment55 | |
56 |
| Multiple line comment | 59 |
60 | /* multiple line 61 | comment */62 | |
63 |
64 | # Multiple line 65 | # comment66 | |
67 |
| Constant | 70 |
71 | uint constant TOTAL_SUPPLY = 10000000;72 | |
73 |
74 | TOTAL_SUPPLY: constant(uint256) = 1000000075 | |
76 |
| Assignment | 79 |
80 | v = 1;81 | |
82 |
83 | v = 184 | |
85 |
| Parallel assignment | 88 |
89 | (x, y) = (0, 1);90 | |
91 |
92 | Tuple to tuple assignment not supported 93 | |
94 |
| Swap | 97 |
98 | (x, y) = (y, x);99 | |
100 | 101 | 102 | | 103 |
| Compound assignment | 106 |
107 | -=, *=, /=, %=, |=, &=, ^=108 | |
109 |
110 | -=, *=, /=, %=, |=, &=, ^=111 | |
112 |
| Increment and decrement | 115 |
116 | i++, ++i, i--, --i117 | |
118 |
119 | i += 1, i -= 1120 | |
121 |
| Null | 124 |
125 | null doesn't exist in Solidity but any unitialized variables take a default value represented by 0 in memory 126 | |
127 |
128 | null doesn't exist in Vyper but any unitialized variables take a default value represented by 0 in memory 129 | |
130 |
| Set variable to default value | 133 |
134 | delete v // doesn't work with mappings135 | |
136 |
137 | v = empty(uint256)138 | |
139 |
| Null test | 142 |
143 | v == 0144 | |
145 |
146 | v == 0147 | |
148 |
| Conditional expression | 151 |
152 | x > 0 ? x : -x153 | |
154 |
155 | Conditional expression not supported 156 | |
157 |
| Contract lifecycle | 160 |||
| Feature | 163 |Solidity | 164 |Vyper | 165 |
| Contract creation | 168 |
169 | Contract c = new Contract(args);170 | |
171 | 172 | 173 | | 174 |
| Contract creation with funding | 177 |
178 | Contract c = new Contract{value: amount}(args);
179 | |
180 | 181 | 182 | | 183 |
| Salted contract creation (CREATE2) | 186 |
187 | Contract c = new Contract{salt: salt}(args);
188 | |
189 | 190 | 191 | | 192 |
| Create forwarder contract | 195 |196 | 197 | | 198 |
199 | contract: address = create_forwarder_to(other_contract, value)200 | |
201 |
| Selfdestruct (Avoid) | 204 |
205 | selfdestruct(refundAddr)206 | |
207 |
208 | selfdestruct(refund_addr)209 | |
210 |
| Interfaces | 213 |||
| Feature | 216 |Solidity | 217 |Vyper | 218 |
| Interfaces | 221 |
222 | interface HelloWorld {
223 | function hello() external pure;
224 | function world(int) external pure;
225 | }
226 | |
227 |
228 | interface HelloWorld: 229 | def hello(): nonpayable 230 | def world(uint256): nonpayable231 | |
232 |
| Interface type | 235 |
236 | interface HelloWorldWithEvent {
237 | event Event();
238 | function hello() external pure;
239 | function world(int) external pure;
240 | }
241 |
242 | contract Test {
243 | bytes4 public hello_world_with_event = type(HelloWorldWithEvent).interfaceId;
244 | }
245 | |
246 | 247 | 248 | | 249 |
| Operators | 252 |||
| Feature | 255 |Solidity | 256 |Vyper | 257 |
| True and false | 260 |
261 | true false262 | |
263 |
264 | True False265 | |
266 |
| Falsehoods | 269 |
270 | false271 | |
272 |
273 | False274 | |
275 |
| Logical operators | 278 |
279 | && || !280 | |
281 |
282 | and or not283 | |
284 |
| Relational operators | 287 |
288 | == != < > <= =>289 | |
290 |
291 | == != < > <= =>292 | |
293 |
| Min and max | 296 |297 | 298 | | 299 |
300 | max(x, y)301 | |
302 |
| Arithmetic operators | 305 |
306 | + - * / % ** unary-307 | |
308 |
309 | + - * / % ** unary-310 | |
311 |
| Integer division | 314 |
315 | /316 | |
317 |
318 | /319 | |
320 |
| Bit operators | 323 |
324 | << >> & | ^ ~325 | |
326 |
327 | << >> & | ^ ~328 | |
329 |
| Binary & hex literals | 332 |
333 | uint x = 0x52 334 | string memory s = hex"52"335 | |
336 |
337 | a: address= 0x14d465376c051Cbcd80Aa2d35Fd5df9910f80543 338 | b: Bytes[32]= b'\x01\x02\x03\x04\x05\x06... (32 bytes) 339 | d: Bytes[1] = 0b00010001340 | |
341 |
| Data structures | 344 |||
| Feature | 347 |Solidity | 348 |Vyper | 349 |
| String type | 352 |
353 | string354 | |
355 |
356 | String[N] # N is a fixed number357 | |
358 |
| Bytes type | 361 |
362 | bytes // dynamic 363 | bytes1, bytes2, ..., bytes32 // packed 364 | bytes[N] // N is a fixed number, unpacked365 | |
366 |
367 | Bytes[N] # N is a fixed number368 | |
369 |
| String literal | 372 |
373 | "don't \"no\"" 374 | 'don"t \'no\''375 | |
376 |
377 | "don't \"no\"" 378 | 'don"t \'no\''379 | |
380 |
| Unicode literal | 383 |
384 | unicode"🍠"385 | |
386 | 387 | 388 | | 389 |
| String length | 392 |
393 | bytes(s).length394 | |
395 |
396 | len(s)397 | |
398 |
| String literal escapes | 401 |
402 | \<newline> (escapes an actual newline) 403 | \\ (backslash) 404 | \' (single quote) 405 | \" (double quote) 406 | \b (backspace) 407 | \f (form feed) 408 | \n (newline) 409 | \r (carriage return) 410 | \t (tab) 411 | \v (vertical tab) 412 | \xNN (hex escape) 413 | \uNNNN (unicode escape)414 | |
415 |
416 | \<newline> (escapes an actual newline) 417 | \\ (backslash) 418 | \' (single quote) 419 | \" (double quote) 420 | \a (bell) 421 | \b (backspace) 422 | \f (form feed) 423 | \n (newline) 424 | \r (carriage return) 425 | \t (tab) 426 | \v (vertical tab) 427 | \ooo (octal escape) 428 | \xNN (hex escape) 429 | \uNNNN (unicode escape) 430 | \uNNNNNNNN (unicode escape)431 | |
432 |
| Are strings mutable? | 435 |
436 | Yes 437 | |
438 |
439 | Yes 440 | |
441 |
| Slice | 444 |
445 | abi.decode(_payload[:4], (bytes4)) 446 | // array slices only implemented for calldata arrays447 | |
448 |
449 | slice(x, _start, _len)450 | |
451 |
| String comparison | 454 |
455 | keccak256(abi.encodePacked(s1)) == keccak256(abi.encodePacked(s2))456 | |
457 |
458 | keccak256(s1) == keccak256(s2)459 | |
460 |
| String concatenation | 463 |
464 | abi.encodePacked(s1, s2)465 | |
466 |
467 | concat(s1, s2)468 | |
469 |
| Array literal | 472 |
473 | [1, 2, 3]474 | |
475 |
476 | [1, 2, 3]477 | |
478 |
| Length | 481 |
482 | a.length483 | |
484 |
485 | len(a)486 | |
487 |
| Empty test | 490 |
491 | a.length == 0492 | |
493 | 494 | 495 | | 496 |
| Lookup | 499 |
500 | a[0]501 | |
502 |
503 | a[0]504 | |
505 |
| Update | 508 |
509 | a[0] = 1;510 | |
511 |
512 | a[0] = 1513 | |
514 |
| Out of bounds access | 517 |
518 | Failing assertion 519 | |
520 |
521 | Failing assertion 522 | |
523 |
| Add new element | 526 |
527 | a.push(3); # Dynamic arrays528 | |
529 | 530 | 531 | | 532 |
| Remove element | 535 |
536 | a.pop(); # Dynamic arrays537 | |
538 | 539 | 540 | | 541 |
| Struct | 544 |
545 | struct Pair {
546 | uint x;
547 | uint y;
548 | } // Creating a struct
549 |
550 | Pair memory pair = Pair(2, 3); // Instantiating a struct variable
551 | require(pair.y > pair.x); // Accessing elements
552 | |
553 |
554 | struct Pair:
555 | x: uint256
556 | y: uint256 # Creating a struct
557 |
558 | pair: Pair = Pair({x: 2, y: 3}) # Instantiating a struct variable
559 | assert pair.y > pair.x # Accessing elements
560 | |
561 |
| Mapping size | 564 |
565 | Impossible to know 566 | |
567 |
568 | Impossible to know 569 | |
570 |
| Lookup | 573 |
574 | m[2]575 | |
576 |
577 | m[2]578 | |
579 |
| Update | 582 |
583 | m[2] = 1;584 | |
585 |
586 | m[2] = 1587 | |
588 |
| Missing key behaviour | 591 |
592 | A mapping has no concept of set keys, a mapping always refers to a hashed value that is the same for a given mapping and key 593 | |
594 |
595 | A mapping has no concept of set keys, a mapping always refers to a hashed value that is the same for a given mapping and key 596 | |
597 |
| Delete key | 600 |
601 | m[2] = 0;602 | |
603 |
604 | m[2] = empty(uint256)605 | |
606 |
| Immutable variables | 609 |
610 | uint immutable x; // have to be assigned in the constructor611 | |
612 | 613 | 614 | | 615 |
| Functions | 618 |||
| Feature | 621 |Solidity | 622 |Vyper | 623 |
| Define function | 626 |
627 | function add2(uint x, uint y) public pure returns (uint) {
628 | return x + y;
629 | }
630 | |
631 |
632 | @external 633 | def add2(x: uint256, y: uint256) -> uint256: 634 | return x + y635 | |
636 |
| Function argument storage location | 639 |
640 | function first(uint[] calldata x) public pure returns (uint) {
641 | // this function doesn't copy x to memory
642 | return x[0];
643 | }
644 |
645 | function first(uint[] memory x) public pure returns (uint) {
646 | // this function first copies x to memory
647 | return x[0];
648 | }
649 | |
650 | 651 | 652 | | 653 |
| Invoke function | 656 |
657 | add2(x, y)658 | |
659 |
660 | add2(x, y)661 | |
662 |
| External function calls | 665 |
666 | c.f{gas: 1000, value: 4 ether}()
667 | |
668 |
669 | c.f() 670 | raw_call(address, data, outsize, gas, value, is_delegate_call)671 | |
672 |
| Control flow | 675 |||
| Feature | 678 |Solidity | 679 |Vyper | 680 |
| If statement | 683 |
684 | if (a > 2) {
685 | ...
686 | else if (a == 0) {
687 | ...
688 | } else {
689 | ...
690 | }
691 | |
692 |
693 | if a > 2: 694 | ... 695 | elif a == 0: 696 | ... 697 | else: 698 | ...699 | |
700 |
| For loop | 703 |
704 | for (uint i = 0; i < 3; i++) {
705 | ...
706 | }
707 | |
708 |
709 | for i in range(3): 710 | ...711 | |
712 |
| While loop | 715 |
716 | while (a > 0) {
717 | ...
718 | }
719 | |
720 | 721 | 722 | | 723 |
| Do-While loop | 726 |
727 | do {
728 | ...
729 | } while (a > 0);
730 | |
731 | 732 | 733 | | 734 |
| Return value | 737 |
738 | return x + y;739 | |
740 |
741 | return x + y742 | |
743 |
| Break | 746 |
747 | break;748 | |
749 |
750 | break751 | |
752 |
| Continue | 755 |
756 | continue;757 | |
758 |
759 | continue760 | |
761 |
| Assert | 764 |
765 | assert(x > y);766 | |
767 |
768 | assert x > y769 | |
770 |
| Require | 773 |
774 | require(x > y);775 | |
776 | 777 | 778 | | 779 |
| Revert | 782 |
783 | require(false, "revert reason")784 | |
785 |
786 | raise "revert reason"787 | |
788 |
| Exception handling | 791 |
792 |
793 | interface DataFeed { function getData(address token) external returns (uint value); }
794 |
795 | contract FeedConsumer {
796 | DataFeed feed;
797 | uint errorCount;
798 | function rate(address token) public returns (uint value, bool success) {
799 | // Permanently disable the mechanism if there are
800 | // more than 10 errors.
801 | require(errorCount < 10);
802 | try feed.getData(token) returns (uint v) {
803 | return (v, true);
804 | } catch Error(string memory /*reason*/) {
805 | // This is executed in case
806 | // revert was called inside getData
807 | // and a reason string was provided.
808 | errorCount++;
809 | return (0, false);
810 | } catch (bytes memory /*lowLevelData*/) {
811 | // This is executed in case revert() was used
812 | // or there was a failing assertion, division
813 | // by zero, etc. inside getData.
814 | errorCount++;
815 | return (0, false);
816 | }
817 | }
818 | }
819 | |
820 | 821 | 822 | | 823 |
| Misc | 826 |||
| Feature | 829 |Solidity | 830 |Vyper | 831 |
| Comments | 834 |
835 | NatSpec conventions for functions: 836 | 837 | /// @author Mary A. Botanist 838 | /// @notice Calculate tree age in years, rounded up, for live trees 839 | /// @dev The Alexandr N. Tetearing algorithm could increase precision 840 | /// @param rings The number of rings from dendrochronological sample 841 | /// @return age in years, rounded up for partial years 842 | 843 | Events: 844 | 845 | /// The address `participant` just registered for the gathering. 846 | event Registered(address participant); 847 | 848 | Special inheritance syntax for contracts: 849 | 850 | /// @inheritdoc OtherContract851 | |
852 |
853 | def foo(): 854 | """ 855 | @author Mary A. Botanist 856 | @notice Calculate tree age in years, rounded up, for live trees 857 | @dev The Alexandr N. Tetearing algorithm could increase precision 858 | @param rings The number of rings from dendrochronological sample 859 | @return age in years, rounded up for partial years 860 | """ 861 | ...862 | |
863 |
| Payment with error on failure (Avoid for Solidity) | 866 |
867 | address.transfer()868 | |
869 |
870 | send(address, value)871 | |
872 |
| Payment with false on failure (Avoid for Solidity) | 875 |
876 | address.send()877 | |
878 | 879 | 880 | | 881 |
| Payment with gas forwarding (WARNING) | 884 |885 | 886 | | 887 |
888 | raw_call(address, data, outsize, gas, value, is_delegate_call)889 | |
890 |
| Event logging | 893 |
894 | event Deposit( 895 | address indexed _from, 896 | bytes32 indexed _id, 897 | uint _value 898 | ); 899 | 900 | emit Deposit(msg.sender, _id, msg.value);901 | |
902 |
903 | event Deposit: 904 | _from: indexed(address) 905 | _id: indexed(bytes32) 906 | _value: uint256 907 | 908 | log Deposit(msg.sender, _id, msg.value)909 | |
910 |
| Units, global constants and type ranges | 913 |
914 | 1 ether 915 | 1 wei 916 | 1 gwei 917 | 1 seconds 918 | 1 minutes 919 | 1 hours 920 | 1 days 921 | 1 weeks 922 | 1 years // deprecated 923 | type(uint).min 924 | type(uint).max 925 | type(int8).min 926 | type(int8).max 927 | ...928 | |
929 |
930 | ZERO_ADDRESS 931 | as_wei_value(1, "finney") 932 | as_wei_value(1, "szabo") 933 | as_wei_value(1, "wei") 934 | as_wei_value(1, "babbage") 935 | as_wei_value(1, "shannon") 936 | EMPTY_BYTES32 937 | MAX_INT128 938 | MIN_INT128 939 | MAX_DECIMAL 940 | MIN_DECIMAL 941 | MAX_UINT256 942 | ZERO_WEI943 | |
944 |
| Block and transaction properties | 947 |
948 | blockhash(blockNumber) 949 | block.coinbase 950 | block.difficulty 951 | block.gaslimit 952 | block.number 953 | 954 | block.timestamp 955 | now // alias for block.timestamp, deprecated 956 | gasleft() 957 | msg.data 958 | msg.gas 959 | msg.sender 960 | msg.sig 961 | msg.value 962 | tx.gasprice 963 | tx.origin964 | |
965 |
966 | blockhash(blockNumber) 967 | block.coinbase 968 | block.difficulty 969 | 970 | block.number 971 | block.prevhash # Same as blockhash(block.number - 1) 972 | block.timestamp 973 | 974 | 975 | 976 | msg.gas 977 | msg.sender 978 | 979 | msg.value 980 | 981 | tx.origin982 | |
983 |