mys 0.151.0

The Mys (/maɪs/) programming language.

WARNING

Mys is still in the very early stages of development. API:s will change, so now is the time to make suggestions! Join the Mys Discord server to get in touch with the developers!

🐁 Mys

The Mys (/maɪs/) programming language - an attempt to create a statically typed Python-like language that produces fast binaries.

Mys is heavily inspired by Python’s syntax and Rust’s packaging.

Source code:

from random.pseudo import random

def main():
    print(random())

Package configuration:

[package]
name = "robot"
version = "0.1.0"
authors = ["Mys Lang <[e-mail]>"]

[dependencies]
random = "*"

Mys is mainly targeting resource constrained single and multi core embedded systems, but is just as useful in desktop environments.

Notable differences to Python:

• Traits instead of classic inheritence.

• Statically typed.

• Bytes and strings are mutable.

• Integers are bound (i32, u32, i64, …).

• Iterators/generators do not (yet?) exist.

• Rust-like generic functions and classes.

• Only packages. No stand alone modules.

• Compiled to machine code. No interpreter.

• Data races and memory corruption possible, but unlikely.

• No async.

• Only from ... import ... is allowed. import ... is not.

• Only functions, enums, traits, classes and variables can be imported, not modules.

Tutorial

If you havn’t already installed Mys, install it as described in the Installation section.

Now, create a package called foo with the command mys new foo, and then enter it. This package is used in throughout the tutorial.

src/main.mys implements the hello world application.

def main():
    print("Hello, world!")

Build and run the application with the command mys run. It prints Hello, world!, just as expected.

src/lib.mys implements the function add() and it’s test test_add(). This examplifies how to test your Mys modules.

def add(first: i32, second: i32) -> i32:
    return first + second

@test
def test_add():
    assert add(1, 2) == 3

Build and run the tests with the command mys test.

Add the bar package as a dependency and use it’s hello() function.

package.toml with the bar dependency added:

[package]
name = "foo"
version = "0.1.0"
authors = ["Mys Lang <[e-mail]>"]

[dependencies]
bar = "*"

src/main.mys importing hello() from the bar module:

from bar import hello

def main(argv: [string]):
    hello(argv[1])

Build and run the new application. Notice how the dependency is downloaded and that mys run universe prints Hello, universe!.

Replace the code in src/main.mys with the code below. It examplifies how to use functions, classes, errors, types and command line arguments. The syntax is almost identical to Python, so many readers should easily understand it.

def func_1(a: i64) -> (i64, string):
    if a == 5:
        text = "Foo"
    else:
        text = "Bar"

    return 2 * a, text

def func_2(a: i64, b: i64) -> i64:
    for i in range(b):
        a += i * b

    return a

def func_3(a: i64) -> {i64: [f64]}:
    return {
        1: [2.0],
        10 * a: [7.5, -1.0]
    }

def func_4():
    try:
        raise GeneralError()
    except:
        print("func_4():      An error occurred.")

def func_5() -> [i64]:
    small: [i64] = []

    for v in [3, 1, 5, 7, 2]:
        if v < 5:
            small.append(v)

    small.sort()
    small.reverse()

    return small

class Calc:
    value: i64

    def triple(self):
        self.value *= 3

def main(argv: [string]):
    value = i64(argv[1])
    print("func_1(value):", func_1(value))
    print("func_2(value):", func_2(value, 1))
    print("func_3(value):", func_3(value))
    func_4()
    print("func_5():     ", func_5())
    calc = Calc(value)
    calc.triple()
    print("calc:         ", calc)

Build and run it.

$ mys run 5
func_1(value): (10, "Foo")
func_2(value): 5
func_3(value): {1: [2], 50: [7.5, -1]}
func_4():      An error occurred.
func_5():      [3, 2, 1]
calc:          Calc(value=15)

Installation

Linux

Install Python 3.8 or later, and then install Mys using pip.

$ pip install mys

You must also have recent versions of g++, make and pylint installed. Optionally install ccache for potentially faster builds.

Windows

1. Install Cygwin. Required packages are gcc-g++, make, python38 and python38-devel. Optionally select ccache as well for potentially faster builds.

2. Start Cygwin and install pip and Mys.

   $ /usr/bin/python3.8 -m easy_install pip
   $ /usr/bin/python3.8 -m pip mys

Loops

while and for loops are available.

while loops run until given condition is false or until break.

for loops can only iterate over ranges, lists, dictionaries, strings and bytes. All but dictionaries supports combinations of enumerate(), slice(), reversed() and zip(). Never modify variables you are iterating over, or the program may crash!

# While.
v = 0

while v < 10:
    if v < 3:
        continue
    elif v == 7:
        break

    v += 1

# Ranges.
for v in range(10):
    if v < 3:
        continue
    elif v == 7:
        break

for i, v in enumerate(range(10, 4, -2)):
    pass

# Lists.
for v in [3, 1]:
    pass

for i, v in enumerate([3, 1]):
    pass

for v, s in zip([3, 1], ["a", "c"]):
    pass

for v in slice([3, 1, 4, 2], 1, -1):
    pass

for v in reversed([3, 1, 4, 2]):
    pass

# Dictionaries.
for k, v in {2: 5, 6: 2}:
    pass

# Strings. 'c' is char.
for c in "foo":
    pass

for i, c in enumerate("foo"):
    pass

# Bytes. 'b' is u8.
for b in b"\x03\x78":
    pass

for i, b in enumerate(b"\x03\x78"):
    pass

Pattern matching

Use pattern matching to promote an object to its class from one of its traits. Pattern matching can match object contents or value as well.

@trait
class Base:
    pass

class Foo(Base):
    pass

class Bar(Base):
    pass

class Fie(Base):
    pass

def handle_message(message: Base):
    # Foo() and Bar() just means these classes with any state. No
    # instance is created, just the type is checked.
    match message:
        case Foo() as foo:
            print("Handling foo.")
        case Bar() as bar:
            print("Handling bar.")
        case _:
            print(f"Unhandled message: {message}")

def numbers(value: i64):
    match value:
        case 0:
            print("Zero integer.")
        case 5:
            print("Five integer.")

def strings(value: string):
    match value:
        case "foo":
            print("Foo string.")
        case _:
            print("Other string.")

def main():
    handle_message(Foo())
    handle_message(Bar())
    handle_message(Fie())
    numbers(0)
    numbers(1)
    numbers(5)
    strings("foo")
    strings("bar")

$ mys run
Handling foo.
Handling bar.
Unhandled message: Fie()
Zero integer.
Five integer.
Foo string.
Other string.

Generics

@generic(T1, T2)
class Foo:
    a: T1
    b: T2

# Type alias.
Bar = Foo[i32, string]

@generic(T)
def fie(v: T) -> T:
    return v

def main():
    print(Foo[bool, u8](True, 100))
    print(Foo("Hello!", 5))
    print(Bar(-5, "Yo"))

    print(fie[u8](2))
    print(fie(1))

$ mys run
Foo(a: True, b: 100)
Foo(a: "Hello!", b: 5)
Bar(a: -5, b: "Yo")
2
1

Classes and traits

• Instance members are accessed with <object>.<variable/method>.

• Implemented trait methods may be decorated with @trait(T).

• Automatically added methods (__init__(), __str__(), …) are only added if missing.

• Decorate with @trait to make a class a trait.

  ToDo: Introduce the trait keyword.

• There is no traditional OOP inheritance. Traits are used instead.

• Traits does not have a state and cannot be instantiated.

Below is a class with a data member value and a method inc().

The constructor def __init__(self, value: i32 = 0) (and more methods) are automatically added to the class as they are missing.

class Foo:
    value: i32

    def inc(self):
        self.value += 1

def main():
    print("f1:")
    f1 = Foo(0)
    print(f1)
    f1.inc()
    print(f1)

    print("f2:")
    f2 = Foo(5)
    print(f2)

$ mys run
f1:
Foo(value=0)
Foo(value=1)
f2:
Foo(value=5)

Enumerations

Enumerations are integers with named values, similar to C.

ToDo: Introduce the enum keyword.

@enum
class Color:
    Red
    Green
    Blue

@enum(u8)
class City:
    Linkoping = 5
    Norrkoping
    Vaxjo = 10

def main():
    assert Color(0) == Color.Red

    # Color(3) raises ValueError since 3 is not a color.

Function and method overloading

Functions and methods can be overloaded.

Calls the first defined function that matches given parameter and return value types.

# func 1
def neg(v: i16) -> i16:
    return -v

# func 2
def neg(v: i8) -> i8:
    return -v

# func 3
def neg(v: i8) -> i16:
    return -v

def main():
    v1 = neg(-5)  # Calls func 1.
    v2 = neg(i8(-5))  # Calls func 2.
    v3: i8 = neg(-5)  # Calls func 2.
    v4: i16 = neg(i8(-5))  # Calls func 3.
    v5: i8 = neg(i16(-5))  # Error. No matching function.

Types

Primitive types

Primitive types are always passed by value.

Type	Example	Comment
i8, i16, i32, i64	1, -1000	Signed integers of 8, 16, 32 and 64 bits.
u8, u16, u32, u64	1, 1000	Unsigned integers of 8, 16, 32 and 64 bits.
f32, f64	5.5, -100.0	Floating point numbers of 32 and 64 bits.
bool	True, False	A boolean.
char	'a'	A unicode character. '' is not a character.

i8, i16, i32, i64, u8, u16, u32 and u64

iN(number: string, base: u32)  # String to signed integer. Uses string
                               # prefix (0x, 0o, 0b or none) if base is 0,
                               # otherwise no prefix is allowed.
uN(number: string, base: u32)  # String to unsigned integer. Uses string
                               # prefix (0x, 0o, 0b or none) if base is 0,
                               # otherwise no prefix is allowed.
iN(value: f32/f64)             # Floating point number to signed integer.
uN(value: f32/f64)             # Floating point number to unsigned integer.
iN(value: bool)                # Boolean to signed integer (0 or 1).
uN(value: bool)                # Boolean to unsigned integer (0 or 1).
i32(value: char)               # Character to singed integer.
==                             # Comparisons.
!=
<
<=
>
>=
^                              # Bitwise exclusive or.
&                              # Bitwise and.
|                              # Bitwise or.
+                              # Add.
-                              # Subtract.
*                              # Multiply.
/                              # Divide (round down).
%                              # Modulus.
~                              # Complement.
^=                             # Bitwise exclusive or in place.
&=                             # Bitwise and in place.
|=                             # Bitwise or in place.
+=                             # Add in place.
-=                             # Subtract in place.
*=                             # Multiply in place.
/=                             # Divide in place.
%=                             # Modulus in place.
~=                             # Complement in place.

f32 and f64

fN(number: string)  # String to floating point number.
fN(value: iN/uN)    # Integer to floating point number.
fN(value: bool)     # Boolean to floating point number (0 or 1).
==                  # Comparisons.
!=
<
<=
>
>=
+                   # Add.
-                   # Subtract.
*                   # Multiply.
/                   # Divide.
+=                  # Add in place.
-=                  # Subtract in place.
*=                  # Multiply in place.
/=                  # Divide in place.

bool

bool(value: iN/uN)    # Integer to boolean. 0 is false, rest true.
bool(value: f32/f64)  # Floating point number to boolean. 0.0 is false,
                      # rest true.

char

char(number: i32)
+=(value: i32)         # Add given value.
+(value: i32) -> char  # Add given value.
-=(value: i32)         # Subtract given value.
-(value: i32) -> char  # Subtract given value.
==                     # Comparisons.
!=
<
<=
>
>=

Complex types

Complex types are always passed by reference.

Type	Example	Comment
string	"Hi!"	A sequence of unicode characters.
bytes	b"\x00\x43"	A sequence of bytes.
tuple(T1, T2, ...)	(5.0, 5, "foo")	A tuple with items of types T1, T2, etc.
list(T)	[5, 10, 1]	A list with items of type T.
dict(TK, TV)	{5: "a", -1: "b"}	A dictionary with keys of type TK and values of type TV.
class Name	Name()	A class.

string

__init__()                              # Create an empty string. Same as "".
__init__(character: char)               # From a character.
__init__(other: string)                 # From a string.
__init__(length: u64)
to_utf8(self) -> bytes                  # To UTF-8 bytes.
from_utf8(utf8: bytes) -> string
+=(self, value: string)                 # Append a string.
+=(self, value: char)                   # Append a character.
+(self, value: string) -> string        # Add a string.
+(self, value: char) -> string          # Add a character.
==(self)                                # Comparisons.
!=(self)
<(self)
<=(self)
>(self)
>=(self)
*(self, count: u64)                     # Repeat.
*=(self, count: u64)                    # Repeat in place.
[]=(self, index: u64, character: char)  # Set a character.
[](self, index: u64) -> char            # Get a character.
[]=(self,                               # Set a substring.
    begin: i64,
    end: i64,
    step: 64,
    value: string)
[](self,                                # Get a substring.
   begin: i64,
   end: i64,
   step: i64) -> string
__in__(self, value: char) -> bool       # Contains character.
__in__(self, value: string) -> bool     # Contains string.
starts_with(self,                       # Return true if string starts with given substring.
            substring: string) -> bool
split(self,                             # Split into list of strings with given
      separator: string) -> [string]    # separator string.
join(self, parts: [string]) -> string   # Join given list of strings with the string
                                        # itself.
strip(self, chars: string)              # Strip leading and trailing characters in place.
lstrip(self, chars: string)             # Strip leading characters in place.
rstrip(self, chars: string)             # Strip trailing characters in place.
lower(self)                             # Make string lower case in place.
upper(self)                             # Make string upper case in place.
casefold(self)                          # Stronger variant of lower that
                                        # should be used when doing case insensitive comparison.
to_lower(self) -> string                # Return a new lower case string.
to_upper(self) -> string                # Return a new upper case string.
to_casefold(self) -> string             # Return a new case folded string.
find(self,                              # Find the first occurrence of given character
     sub: char,                         # within given limits. Returns -1 if not found.
     start: i64 = 0,
     end: i64 = <length>) -> i64
find(self,                              # Find the first occurrence of given substring
     sub: string,                       # within given limits. Returns -1 if not found.
     start: i64 = 0,
     end: i64 = <length>) -> i64
cut(self,                               # Find the first occurrence of given separator.
    separator: char) -> string          # If found, returns all characters before that,
                                        # and remove them and the separator from the
                                        # string. Returns None and leaves the string
                                        # unmodified otherwise.
replace(self,                           # Replace old with new.
        old: char,
        new: char)
replace(self,                           # Replace old with new.
        old: string,
        new: string)

Only += moves existing data to the beginning of the buffer. Other methods only changes the begin and/or end position(s). That is, strip() and cut() are cheap, but += may have to move the data.

bytes

__init__()                         # Create an empty bytes object. Same as b"".
__init__(other: bytes)             # From a bytes object.
__init__(length: u64)
to_hex(self) -> string             # To a hexadecimal string.
from_hex(data: string) -> bytes
+=(self, value: bytes)             # Append bytes.
+=(self, value: u8)                # Append a number (0 to 255).
+(self, value: bytes) -> bytes     # Add bytes.
+(self, value: u8) -> bytes        # Add a number (0 to 255).
==(self)                           # Comparisons.
!=(self)
<(self)
<=(self)
>(self)
>=(self)
[]=(self, index: u64, value: u8)
[](self, index: u64) -> u8
[]=(self,
    begin: u64,                    # Set subbytes.
    end: u64,
    step: u64,
    value: bytes)
[](self,
   begin: u64,                     # Get subbytes.
   end: u64,
   step: u64) -> bytes
__in__(self, value: u8) -> bool    # Contains value.

tuple

==(self)                         # Comparisons.
!=(self)
<(self)
<=(self)
>(self)
>=(self)
[]=(self, index: u64, item: TN)  # Set item at index. The index  must be known at
                                 # compile time.
[](self, index: u64) -> TN       # Get item at index. The index must be known at
                                 # compile time.

list

__init__()                      # Create an empty list. Same as [].
__init__(other: [T])            # From a list.
__init__(values: {TK: TV})      # From a dict. Each key-value pair becomes a
                                # tuple.
__init__(length: u64)
+=(self, value: [T])            # Append a list.
+=(self, value: T)              # Append an item.
==(self)                        # Comparisons.
!=(self)
[]=(self, index: u64, item: T)
[](self, index: u64) -> T
[]=(self,                       # Set a sublist.
    begin: u64,
    end: u64,
    step: u64,
    value: [T])
[](self,                        # Get a sublist.
   begin: u64,
   end: u64,
   step: u64) -> [T]
__in__(self, item: T) -> bool   # Contains item.
sort(self)                      # Sort items in place.
reverse(self)                   # Reverse items in place.

dict

__init__()                        # Create an empty dictionary. Same as {}.
__init__(other: {TK: TV})         # From a dict.
__init__(pairs: [(TK, TV)])       # Create from a list.
==(self)                          # Comparisons.
!=(self)
[]=(self, key: TK, value: TV)     # Set value for key.
[](self, key: TK) -> TV           # Get value for key.
|=(self, other: {TK: TV})         # Set/Update given key-value pairs.
|(self, other: {TK: TV})          # Create a dict of self and other.
get(key: TK, default: TV = None)  # Get value for key. Return default if missing.
__in__(self, key: TK) -> bool     # Contains given key.

Built-in functions

Name	Example	Comment
enumerate()	enumerate([3, -1])	Enumerate given iterable. Only allowed in for loops.
input()	input("> ")	Print prompt and read input until newline.
len()	len("hi")	Get the length of given object.
open()	open("path/to/file")	Opens given file in given mode.
print()	print("Hi!")	Prints given data.
range()	range(10)	A range of numbers. Only allowed in for loops.
reversed()	reversed([2, 1])	Yield items in reversed order. Only allowed in for loops.
slice()	slice([1, 3, 2], 1, -1)	A slice. Only allowed in for loops.
str()	str(10)	Printable represenation of given object.
zip()	zip([3, 5], ["a", "g"])	Yield one item from each iterable. Only allowed in for loops.

Special symbols

__file__        The module file path as a string.
__line__        The module file line as an i64.
__name__        The module name (including package) as a string.
__unique_id__   A unique 64 bits integer.

Errors

All error names ends with Error to distinguish them from other classes. All errors must implement the Error trait.

+-- GeneralError
+-- UnreachableError
+-- NotImplementedError
+-- KeyError
+-- ValueError
+-- FileNotFoundError
+-- NoneError
+-- SystemExitError

Functions and methods must declare which errors they may raise.

@raises(TypeError)
def foo():
    raise TypeError()

@raises(GeneralError, TypeError)  # As foo() may raise TypeError.
def bar(value: i32):
    match value:
        case 1:
            raise GeneralError()
        case 2:
            foo()
        case 3:
            try:
                raise ValueError()
            except ValueError:
                pass

Assertions

Use the assert keyword to check that given condition is true.

assert True
assert 1 != 5
assert 1 in [1, 3]
v = 1
assert v == 2

The AssertionError error is raised if the condition is not true.

AssertionError: 1 == 2 is not true

Assertions are always compiled into test and debug binaries, but not by default into optimized application binaries.

Numeric literals

There are no numeric literal suffixes. Its type is always deduced from its context.

In inferred variable type assignments the numeric literals are their base type. Integers are i64 and floats are f64.

def main():
    a = 1  # 1 is i64
    b = 1.0  # 1.0 is f64

Comparisions and arithmetics makes numeric literals the same type as the other value’s type.

def main():
    a: u64 = 1  # 1 is u64
    b: u8 = 1 + 1  # 1 and 1 are u8
    c = u8(1 + 1)  # 1 and 1 are u8
    d = u8(1 + i16(-1))  # 1 and -1 are i16

    if a == 2:  # 2 is u64
        pass

    if (1 + 3) * a == 8:  # 1, 3 and 8 are u64
        pass

    if (1 + 3) * 2 == 8:  # 1, 3, 2 and 8 are i64
        pass

    if u8(1 + 3) == 8:  # 1, 3 and 8 are u8
        pass

Passing numeric literals to functions makes them the same type as the parameter types. First defined matching function is called.

def foo(a: i16, b: f32):
    pass

# bar 1
def bar(a: u8) -> i16:
    return i16(a)

# bar 2
def bar(a: u16) -> i32:
    return i32(a)

def main():
    foo(-44, 3.2)  # -44 is i16 and 3.2 is f32

    if bar(1 + 3) == 8:  # 1 and 3 are u8 and 8 is i16 (bar 1)
        pass

    if bar(1 + u16(3)) == 8:  # 1 and 3 are u16 and 8 is i32 (bar 2)
        pass

    if bar(1 + 3) == i32(8):  # 1 and 3 are u16 and 8 is i32 (bar 2)
        pass

Global variables

Their types can’t be inferred (for now).

Their names must be upper case snake case.

Initialized in import order starting from the first import in main.mys. Circular dependencies between variables during initialization is not allowed.

Given the code below, the global variables are initialized in this order:

1. B = -2 (from bar.mys)

2. Z = 5 (from bar.mys)

3. C = 99 (from fie.mys)

4. Y = 2 * Z (from foo.mys)

5. A = -1 (from foo.mys)

6. X = Y + 5 (from main.mys)

main.mys:

from .foo import Y

X: i32 = Y + 5

def main():
    print(X)

foo.mys:

from .bar import Z
from .fie import C

Y: i32 = 2 * Z
A: i32 = C

bar.mys:

B: i32 = -2
Z: i32 = 5

fie.mys:

C: i32 = 99

Type conversions

Implicit type conversions are only supported for numeric literals and traits.

Extending Mys with C++

Extending Mys with C++ is extremly easy and flexible. Strings that starts with mys-embedded-c++ are inserted at the same location in the generated code.

def main():
    a: i32 = 0
    b: i32 = 0

    """mys-embedded-c++

    b = 2;
    a++;
    """

    print("a + b:", a + b)

Packages

A package contains modules that other packages can import from. Most packages contains a file called lib.mys, which is imported from with from <package> import <function/class/variable>.

Packages that contains src/main.mys produces executables when built. Such packages may also be imported from by other packages, in which case src/main.mys is ignored.

A package:

my-package/
├── LICENSE
├── package.toml
├── pylintrc
├── README.rst
└── src/
    ├── lib.mys
    └── main.mys         # Only part of packages that can build executables.

The mys command line interface:

mys new      Create a new package.
mys build    Build the appliaction.
mys run      Build and run the application.
mys test     Build and run tests.
mys clean    Remove build output.
mys lint     Perform static code analysis.
mys publish  Publish a release.
mys install  Install an application from local package or registry.

Importing functions, enums, traits, classes and variables

Import functions, enums, traits, classes and variables from modules in other packages with from <module> import <name>.

Import functions, enums, traits, classes and variables from modules in current package with from .<module> import <name>. One . per directory level.

Use from <module> import <name> as <new-name> to use a custom name.

• Imports are private. They cannot be exported.

• Circular imports are allowed.

• A module is private if its name or any directory in its path starts with an underscore.

• A private module can only be imported from by other modules in the same package.

• All public definitions in a private module can only be used by other modules in the same package.

• Imports from modules within the same package must be relative.

Here are a few examples:

from mypkg1 import func1                   # Imports from mypkg1/src/lib.mys.
from mypkg2.subpkg1.mod1 import func2 as func3
from mypkg2 import Class1
from mypkg2 import var1
from ..mod1 import func4                   # Imports from ../mod1.mys.
from ...subpkg2.mod1 import func5          # Imports from ../../subpkg2/mod1.mys.
from . import func6                        # Imports from lib.mys in the same
                                           # folder.
# from mypkg2._mod1 import func7           # Not allowed as _mod1 is private.
# from mypkg2._subpkg1.mod1 import func8   # Not allowed as _subpkg1 and all its
                                           # content is private.
from ._mod1 import func7                   # Imports from private _mod1.mys.
from ._subpkg1.mod1 import func8           # Imports from private _subpkg1/mod1.mys.

def foo():
    func1()
    func3()
    Class1()
    print(var1)
    func4()
    func5()
    func6()

List of packages

Some works, some does not even compile. Big work in progress!

• argparse - Command line argument parser.

• base64 - Base64 encoding and decoding.

• bits - Basic bits operations.

• json - JSON encoding and decoding.

• log - Logging facilities.

• math - Basic math operations.

• random - Random numbers.

• sqlite - SQLite.

• system - System services.

• time - Date and time.

Memory management

Integers and floating point numbers are allocated on the stack, passed by value to functions and returned by value from functions, just as any C++ program.

Strings, bytes, tuples, lists, dicts and classes are normally allocated on the heap and managed by C++ shared pointers. Objects that are known not to outlive a function are allocated on the stack.

Reference cycles are not detected and will result in memory leaks.

There is no garbage collector.

Build options

--optimize {speed, size, debug}: Optimize the build for given level. Optimizes for speed by default.

--unsafe: Disable runtime safety checks for faster and smaller binaries.

Disables:

• Implicit None checks.

• list, string and bytes out of bounds checks.

• Signed integer overflow checks.

• Default variable and data member initializations.

• Message ownership checks.

--no-ccache: Do not use Ccache.

Mys tool configuration

The mys command line tool can be configured to fit your development environment.

NOTE: It’s currently not possible to configure anything.

Search order:

1. The environment variable MYS_CONFIG.

2. The file ~/.config/mys/config.toml

Text editor settings

Visual Code

Use the Python language for *.mys files by modifying your files.associations setting.

See the official Visual Code guide for more detils.

"files.associations": {
    "*.mys": "python"
}

Emacs

Use the Python mode for *.mys files by adding the following to your .emacs configuration file.

(add-to-list 'auto-mode-alist '("\\.mys\\'" . python-mode))

Build process

mys build, mys run and mys test does the following:

1. Use Python’s parser to transform the source code to an Abstract Syntax Tree (AST).

2. Generate C++ code from the AST.

3. Compile the C++ code with g++.

4. Link the application with g++.

Calling mys from GNU Make recipe

mys uses make internally. Always prepend the command with + to share jobserver.

Contributing

It’s usually a good idea to add a test in tests/files/<name>.mys and execute with make test -j 8 ARGS="-k <pattern>.

Add positive and negative tests in tests/test_mys.py.

Build and run all tests in parallel with make test-parallel -j 8.

Build and run all tests in parallel and all examples with make -j 8.

Open htmlcov/index.html for code coverage.

Development environments

Ubuntu

Install tools, clone the repo and run tests and examples.

$ sudo apt install git g++ make pylint ccache
$ git clone ssh://[e-mail]/mys-lang/mys
$ python -m pip install -r mys/requirements.txt
$ python -m pip install coverage pylint
$ cd mys
$ make

Windows

The Mys project is built in Cygwin.

1. Install Cygwin. Required packages are gcc-g++, make, python38, ccache, git and python38-devel.

2. Start Cygwin and do the following one time setup.

   $ ln -s /usr/bin/python3.8 /usr/bin/python
   $ python -m easy_install pip
   $ git clone ssh://[e-mail]/mys-lang/mys
   $ python -m pip install -r mys/requirements.txt
   $ python -m pip install coverage pylint

3. Run tests and examples.

   $ cd mys
   $ export PYTHONUTF8=1  # Probably needed.
   $ make

Mocking

from random.pseudo import random

def add(value: f64) -> f64:
    return value + random()

def test_add():
    random_mock_once(5.3)
    assert add(1.0) == 6.3