mlang
Simple programming language using LLVM, flex and bison.
Table of Contents
Installation
Dependencies
- LLVM 11
- Clang
- flex and bison
- CMake 3.17
Build
0. Setup LLVM
See this guide
1. Clone this repository
git clone https://github.com/MFori/mlang.git
2. Go to build directory
cd mlang
cd build
Note: Step 3 and 4 can be skipped by running build.bat file.
3. Run cmake (tested with Visual Studio)
cmake .. -G "Visual Studio 16 2019"
4. Build mlang
Must be build with the same configuration as your LLVM/Clang build (Debug,Release,...)
-
Using Visual Studio
Open mlang.sln (generated in build directory) in Visual Studio and compile it
-
From Command Line
cd build
cmake --build . --config Release
-
Other IDE
Open project with any other IDE with support for cmake and build it using Visual Studio compiler (tested with Clion).
5. Done
After that mlang.exe (and other stuff) is generated. Output path depends on step 4. build/src/Release for Visual Studio, cmake-build-release for Clion,..
Getting Started
Hello World
samples/hello_world.mlang
func helloWorld() {
println("Hello World")
}
helloWorld()
Usage
mlang.exe hello_world.mlang -h -d -r
- -h (--help): show help
- -d (--debug): disable code optimizer
- -r (--run): directly run code (using JIT)
If run is disabled, LLVM-IR for the parsed file is outputed (hello_world.mlang.ir) and also executable (hello_world.exe) is generated.
Language Syntax
Identifiers
Identifier can be any word including underscore and digits and must start with letter ([a-zA-Z][a-zA-Z0-9_]*).
Identifiers are used for variable and function names and they are case sensitive.
Variables
Variables can be declared with keywords var and val.
varis used for mutable variablesvalis used for constants
When declaring, variable must be always initialized. Type of variable is automatically deducted from initializing value.
Variable is only visible in its scope (program block) and can be shadowed by any variable with same name inside sub block.
val a = 1 // constant
var b = 2 // reasiggneable
func someFunction(Int x) { // x is var and can be reassigned
val b = x // shadows first b
x = 0
}
Data Types
There is support for Int, Double, Char, Bool, String data types. Mlang is strongly typed language with static type check. You can use buildin cast functions.
Int
A 64 bit integer
val myInt = 1
Double
A 64 bit floating point real
val myDouble1 = 1.5 // 1.5
val myDouble2 = .1 // 0.1
val myDouble3 = 1.e2 // 100.0
val myDouble4 = .1e-1 // 0.01
Char
An 8 bit character. There are two ways for creating char literals. First using @ and required character or @@ and ascii value of required character.
val ch1 = @A
val ch2 = @@65
if (ch1 == ch2) { // always true
}
Bool
A bool value, literals can be true and false.
val b1 = true
val b2 = false
String
String is internally represented as char array and has all features like other arrays. String is enclosed in " or '. A quote inside string must be escaped by \.
String can be created with literal or by calling String(Int size) function. If second case string is created on heap and must be freed using rm keyword.
val str1 = "This is a \"string\"".
val str2 = String(10)
rm str2
There is special expression for joining mutiple strings. To join string insert them isnside (. and .) symbols separed by comma. The resulting stream is created on heap and must be freed.
val res = (. str1, " and ", str2 .)
rm res
You can access and set Char at index like with any other array.
Arrays
Arrays are available for all data types (except Char, but there is String). Array is created by calling appropriate function passing arrays size.
IntArray(10)
DoubleArray(10)
BoolArray(10)
String(10)
To access (or assign) array element at index use [index] expression. Array size is internally stored asside with array items and during access index is validated against array bounds. To get array size you can use buildin function sizeOf(array).
val arr = IntArray(10)
arr[0] = 1
arr[10] = 1 // runtime error index out of range
val i = arr[1]
All arrays are created on heap and must be freed with rm keyword.
rm arr
Functions
Functions are declared with keyword func followed with function name (identifier), parameters and return type.
Body of function is inside { }. Parameters are specified by type and name (parameters are mutable, like var variables).
func myFunction(Int param1, DoubleArray param2): Bool {
return true
}
Primitive data types (Int, Double, Bool, Char) are passed by value, arrays (and string) are passed by reference.
func processArray(IntArray arr) {
arr[0] = -1
}
val array = IntArray(10)
processArray(arr)
println(toString(arr[0])) // -1
Return statement is optional and then is returned last statement.
func getInt(): Int {
1
}
Expressions
Assignment
Assignemnt is via = symbol. Assignemnt results to expression so multiple assignemnt is possible.
var a = b = c = 10
Ternary Operator
C-like ternary operator.
bool-expression ? then : else
val a = b > 10 ? 1.5 : 5.1
Boolean expression
For Int, Double, Char and String:
if (a == b) {...}
if (a != b) {...}
if (a > b) {...}
if (a < b) {...}
if (a >= b) {...}
if (a <= b) {...}
For Bool:
if (true) {...}
if (not true) {...}
if (b1 and b2) {...}
if (b1 or b2) {...}
Binary operator
For Int, Double and Char:
a + b
a - b
a * b
a / b
For Bool:
a and b
a or b
Unary operator
For Int, Double and Char:
i++ // return i and then increase i by one
++i // increase i by one and return i
-i
For Bool:
not b
Control Expressions
If-else
Else is optional.
if (bool-expression) {
statements
} else {
statements
}
While
while (bool-expression) {
statements
}
var i = 10
while (i > 0) {
println(toString(i))
i--
}
Do-While
do {
statements
} while (bool-expression)
do {
i--
} while (i > 0)
For
For loop works only with Int variable which is automatically created and initialized on start bound of range. Step size of optional (default is 1) and can be Int literal or Int expression.
for (var in range) { statements }
for (var in range step step-size) { statements }
Range
Range is specified by bounds (can be literals or expressions) and keyword to or until.
for (i in 0 to 10) {...} // i in [1, 10], 10 is included
for (i in 0 until 10) {...} // i in [0, 10), 10 is excluded
val start = 0
val end = 100
val s = 2
for (i in start to end step s) {
println(toString(i)) // prints 0, 2, 4, .., 100
}
ForEach
ForEach loops through array (or string). Loop variable is automatically created and typed to array element type.
for (var in array) { statements }
val array = IntArray(20)
for (i in array) {
println(toString(i))
}
Break
break keyword can be used inside loops (for, foreach, while, do-while) and jump right after loop.
for (i in 0 to 10) {
if (i > 5) {
break
}
}
Entry Point
In mlang any code can be outside of functions and is automatically executed on startup. However if you want use c-like main function, there is possibility for that. Just create main function like below. If you have created main function and at the same time have some code outside of functions, at first the code outside is perfomed and after that main function is executed.
println("Outside 1") // called fist
func main() {
// is called automatically
println("Hello World") // called third
}
println("Outside 2") // called second
Note: Passing arguments to main function is currently not possible.
Import
Importing other file is possible via the import keyword. Path is relative to current file.
import other-file.mlang
import dir/another-file.mlang
Comments
There is C-like comments support in mlang.
One Line
One line comments starts with //. All characters until end of line are ignored.
Multi Line
Multi line comment starts with /* and ends with */. All characters between are ignored.
Terminators
Grammar uses semicolons as productions terminators, but lexer is automatically inserting them (like GoLang do). So semicolons are optional.
Build-in Functions
Note: for the functions to work is necessary that file buildins.bc (which is generated during build) is in same directory as mlang.exe
Works like c's printf. Fist arguments is string with format, then goes arguments for that format.
val name = "Martin"
val age = 23
print("Name: %s, age: %d", name, age)
println
Same as print, bud add new line after text.
read
Reads one character from stdin.
val ch = read()
readLine
Reads one line from stdin.
val line = readLine()
sizeOf
Returns size of array or string.
val arr = IntArray(10)
val size = sizeOf(arr) // 10
len
Returns length of string - number of characters until '\0' or end of string.
val str = "Hello World"
var l = len(str) // 11
val str2 = String(20)
l = len(str2) // 0
val size = sizeOf(str2) // 20
rm str2
Cast functions
There are cast functions available for every datatype:
toInt(...)
toDouble(...)
toBool(...)
toChar(...)
toString(...)
Note: toString create String on stack, there is no need to free memory using rm keyword.