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releases.md

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Below you can find release notes for each major Codon release, listing improvements, updates, optimizations and more for each new version.

v0.15

Union types

Codon adds support for union types (e.g., Union[int, float]):

def foo(cmd) -> Union:
    if cmd == 'int': return 1
    else: return "s"
foo('int')        # type is Union[int,str]
5 + foo('int')    # 6
'a' + foo('str')  # as

Dynamic inheritance

Dynamic inheritance and polymorphism are now supported:

class A:
    def __repr__(): return 'A'
class B(A):
    def __repr__(): return 'B'
l = [A(), B(), A()]  # type of l is List[A]
print(l)  # [A, B, A]

This feature is still a work in progress.

LLVM upgrade

Upgraded to LLVM 15 (from 12). Note that LLVM 15 now uses opaque pointers, e.g. ptr instead of i8* or i64*, which affects @llvm functions written in Codon as well as LLVM IR output of codon build.

Standard library

random module now matches Python exactly for the same seed.

v0.14

GPU support

GPU kernels can now be written and called in Codon. Existing loops can be parallelized on the GPU with the @par(gpu=True) annotation. Please see the docs for more information and examples.

Semantics

Added -numerics flag, which specifies semantics of various numeric operations:

  • -numerics=c (default): C semantics; best performance
  • -numerics=py: Python semantics (checks for zero divisors and raises ZeroDivisionError, and adds domain checks to math functions); might slightly decrease performance.

Types

Added float32 type to represent 32-bit floats (equivalent to C's float). All math functions now have float32 overloads.

Parallelism

Added collapse option to @par:

@par(collapse=2)  # parallelize entire iteration space of 2 loops
for i in range(N):
    for j in range(N):
        do_work(i, j)

Standard library

Added collections.defaultdict.

Python interoperability

Various Python interoperability improvements: can now use isinstance on Python objects/types and can now catch Python exceptions by name.

v0.13

Language

Scoping

Scoping was changed to match Python scoping. For example:

if condition:
    x = 42

print(x)

If condition is False, referencing x causes a NameError to be raised at runtime, much like what happens in Python. There is zero new performance overhead for code using the old scoping; code using the new scoping as above generates a flag to indicate whether the given variable has been assigned.

Moreover, variables can now be assigned to different types:

x = 42
print(x)  # 42
x = 'hello'
print(x)  # hello

The same applies in Jupyter or JIT environments.

Static methods

Added support for @staticmethod method decorator. Class variables are also supported:

class Cls:
    a = 5  # or "a: ClassVar[int] = 5" (PEP 526)

    @staticmethod
    def method():
        print('hello world')

c = Cls()
Cls.a, Cls.method(), c.a, c.method()  # supported

Tuple handling

Arbitrary classes can now be converted to tuples via the tuple() function.

Void type

The void type has been completely removed in favor of the new and Pythonic NoneType, which compiles to an empty LLVM struct. This does not affect C interoperability as the empty struct type is replaced by void by LLVM.

Standard library

The re module is now fully supported, and uses Google's re2 as a backend. Future versions of Codon will also include an additional regex optimization pass to compile constant ("known at compile time") regular expressions to native code.

C variables

Global variables with C linkage can now be imported via from C import:

# assumes the C variable "long foo"
from C import foo: int
print(foo)

Parallelism

Numerous improvements to the OpenMP backend, including the addition of task-based reductions:

total = 0
@par
for a in some_arbitrary_generator():
    total += do_work(a)  # now converted to task reduction

Python interoperability

Included revamped codon module for Python, with @codon.jit decorator for compiling Python code in existing codebases. Further improved and optimized the Python bridge. Please see the docs for more information.

Codon IR

New capture analysis pass for Codon IR for improving tasks such as dead code elimination and side effect analysis. This allows Codon IR to deduce whether arbitrary, compilable Python expressions have side effects, capture variables, and more.

Code generation and optimizations

A new dynamic allocation optimization pass is included, which 1) removes unused allocations (e.g. instantiating a class but never using it) and 2) demotes small heap allocations to stack (alloca) allocations when possible. The latter optimization can frequently remove any overhead associated with instantiating most classes.

Command-line tool

The codon binary can now compile to shared libraries using the -lib option to codon build (or it can be deduced from a .so or .dylib extension on the output file name).

Errors

Added support for multiple error reporting.