Mutan
Mutan is a C-Like language for the Ethereum project. Mutan supports a full, statically typed higher level language that compiles to native Ethereum Assembler. Repo will be moved.
An online editor and compiler can be found here
go get -u github.com/obscuren/mutan/mutan
The syntax is specified using Extended Backus-Naur Form (EBNF):
digit excluding zero = "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
digit = "0" | digit excluding zero ;
The following keywords are reserved and may not be used as identifiers
this if else return exit for asm nil transact create call sizeof true false
Mutan contains the following operators and delimiters
+ ** = | ( )
- ^ == & { }
* >= ++ ; << >>
/ <= -- ! :=
Numeric types in Mutan can only be represented by integer values and are architecture-independent. They are all represented in big endian byte order. Signed integers aren't supported (yet?)
int8 the set of all _unsigned_ integers (0 to 255)
int16 the set of all _unsigned_ integers (0 to 65535)
int32 the set of all _unsigned_ integers (0 to 4294967295)
int64 the set of all _unsigned_ integers (0 to 18446744073709551615)
int256 the set of all _unsigned_ integers (0 to 1.1579209e+77)
addr special type for storing addresses with a size of 20 bytes
big type int256
int type int32
byte, bool type int8
Numbers may be specified in decimal and hexadecimal format.
Arrays are of theoretical unlimited length
ArrayType = ElementType "[" Number "]" .
ElementType = Type .
The following are all valid arrays:
int16[10] a
int32[10] b
big[10] c
A declaration binds an identifier to a type. Every identifier must be declared. No identifier may be declared twice. All declarations are global.
Declaration = TypeDecl .
A declaration can be done in several ways. First and foremost every identifier must be declared either with a type or a variant. Variants can be created in two separate ways, either with the var keyword or by using the := assignment operator.
var a = "a"
string b = "b"
c := "c"If a variable has been declared as a variant and assigned, it's no longer possible to re-assign it with a different type.
a := 10
a = "hello" // ErrorTypes:
var bool int int8 int16 int32 int64 int256 big string
Statement = Declaration | Block | IfStmt | ForStmt | Expression | Lambda
Expression = Ptr | Number | Hex | String | Identifier .
Ptr = Identifier | "nil" .
Number = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" .
Hex = "0x" "a" | "b" | "c" | "d" | "e" | Number .
String = """ * """
Identifier = * .
Blocks contain, but not necessarily, contain lists of Statements within matching brackets.
Block = "{" StatementList "}" .
StatementList = { Statement ";" } .
If statements specify the conditional execution of two branches according to the value of an expression. If the expression evaluated to true, the "if" branch is executed, else, if present, the else branch is executed.
IfStmt = "if" [ SimpleStmt ";" ] Expression Block [ "else" Block ] .
if x < 10 {
x = maximum
}The expression may be preceded by a simple statement which executes before the boolean expression
if int8 x = this.Value(); x < 10 {
x = maximum
} else {
y = 10
}A "for" statements specifies repeated execution of a block, the iteration is controlled by a conditional block.
ForStmt = "for" [ InitStmt ] ";" [ Condition ] ";" [ PostStmt ] .
InitStmt = SimpleStmt .
PostStmt = SimpleStmt .
A "for" in it's simplest form is a C-Like "while" statement (therefor Mutan doesn't have a "while")
for a < b {
a = a * 2
}A "for" statement in it's purest form is controlled my a initialiser, condition and a post statement which will be executed at the end of the Block
for int8 a = 0; a < b; a++ {
b = b - 1
}for cond { T() } is the same as for ; cond ; { T() }
for cond; post { T() } is the same as for ; cond; post { T() }
String literals are supported by enclosing a line of text with matching quotes "string". Strings can be assigned to variables and stored in memory. Storing strings in memory only allows storing up to 32 bytes. This is due to the limitation of the size that is allowed to be stored in each storage location. If a string with a size larger than 32 bytes is assigned to a storage address it will throw an error.
str := "hello world"
this.store[0] = "hello world"A lambda in mutan is a semi lambda and, at the time of writing, can only be used in a return statement. A lambda will compile the given code, enclosed by brackets { // code }. Lambdas are allowed to be of arbitrary size and take up as much memory as needed.
a := "hello"
return lambda {
a := 20
if a == 20 {
}
}Lambdas have their own scope and do not share any memory outside of their own scope, neither can they use any memory outside of their scope. Lambdas should be viewed as separate instances of code.
var a = "hello"
return lambda {
b := a // Undefined references error
}Mutan comes with a couple build in functions for stopping, creating and transacting between multiple objects and context functions.
"exit()"
Stops the execution of the current call
Success = "call(" Expression, Expression, Expression, Ptr, Ptr ")"
Calls contract specified by the address and executes. Arguments can be passed to the in argument and the return value can be specified by the out parameters. Return a 1 or 0 depending whether this call was success or not.
Success = "transact(" Expression, Expression, Ptr ")"
Handles a transaction between two objects.
Address = "create(" Expression, Expression ")"
Creates a new contract given by script and returns the Address of the transaction.
The following functions relate to the current executing context (i.e. the closure). These build-in functions are prefixed with this..
Method = "this" Dot MethodName "(" [ Expression ] ")" .
Dot = "." .
MethodName = "dataLoad" | "dataSize" | "origin" | "caller" | "gasPrice" | "value" |
"diff" | "prevHash" | "time" | "gasPrice" | "number" | "coinbase" | "gas" .
data Returns the x'th value of the attached data of this call
dataSize Returns the size of the data attached to this call
origin Returns the origin address of this execution
caller Returns the current caller of the closure
gasPrice Returns the gas price attached to this call
value Returns the value attached to this call
balance Returns the value of the current call
diff Returns the current difficulty
prevHash Returns the previous block's hash
time Returns the current block's timestamp
gasPrice Returns the attached call's gas price
number Returns the current block's number
coinbase Returns the current block's coinbase
gas Returns the current call's attached amount of gas
Inline assembler is allowed through the asm keyword
InlineAssembler = "asm" "(" Code ")" .
Code = "abcdefghijklmnopqrstuwvxyz" | "1234567890" .
Mutan has a very basic pre processor that takes any #define and replaces that throughout the source code
Output = "#define" Word [ Expression ] .
#define ADDR 0xe6716f9544a56c530d868e4bfbacb172315bdead
int32 a = 20
int32 b = 10
var str = "hello"
otherStr := "world"
if a < b {
exit()
} else {
// :-)
if !a {
if this.data[0] ** 10 >= 10 {
this.data[0] = 1000;
}
}
}
this.store[a] = 10000
this.store[b] = this.origin()
for int8 i = 0; i < 10; i++ {
int32[10] out
call(0xaabbccddeeff112233445566, 0, 10000, i, out)
}
// tx without input data
transact(0xa78f6abe, 10000, nil)
// no args and return values
call(0xab, 0, 10000, nil, nil)
// create contract
big ret = create(value, 0xaabbccddeeff0099887766552211)
int8 left = 8 << 2
left = left >> 2
asm (
PUSH 10
PUSH 0
MSTORE
)
return lambda {
this.store[0] = "hello"
}