Data Types

Vyper is a statically typed Pythonic language. The type of each variable (state and local) must be specified or at least known at compile-time. Vyper provides several elementary types such as:

bool (boolean)
int256,int32 (signed integer)
uint256,uint32 (unsigned integer)
bytesM (fixed size byte array)
Bytes[100], Bytes[256] (byte array with max size)
String (strings)
decimal (decimals)
address (Ethereum address)

# pragma version 0.4.0

# like Solidity, state variables are by default private visibility
# use `public` keyword to make them public
boo: public(bool)
signed_int: public(int256)
unsigned_int: public(uint64)
fixed_size_bytes: public(bytes32)
dynamic_size_bytes: public(Bytes[256]) #the maximum number of bytes here is 256
string: public(String[13]) #the maximum length of string here is 13
addy: public(address)

# use --enable-decimals flag when compiling Vyper code containing decimal type
decimal_variable: public(decimal)

@deploy
def __init__():
    self.boo = False
    self.signed_int = -100
    self.unsigned_int = 999
    self.fixed_size_bytes = 0xabcd1123f8ae9a65dcc16f95643f2030aa505c6b465c8206e26ae84b525cdacb
    self.dynamic_size_bytes = b"\x01" # b"" syntax indicates content inside quotes is a byte array
    self.string = "Hello, world!"
    self.addy = 0xE2b4795039517653c5Ae8C2A9BFdd783b48f447A
    self.decimal_variable = 22.77

Vyper Differentiators

Requires explicit specification of bit width for integer and byte types (i.e. uint256, int32, bytes32).
Requires explicit specification for dynamic arrays and strings (i.e. String[13]).
Floating point numbers (decimal) are supported.
Use --enable-decimals flag when compiling Vyper code containing decimal type.
Converting decimal to uint256 or int256 will result in truncation (i.e., 7.5 becomes 7).

Data Types

Further Reading: