index.md

title	PRIK
description	Turn Fortran functions, modules, arrays, and derived types into natural Python APIs
audience	users
prerequisites	none
related	user/getting-started/index.md, user/getting-started/installation.md, user/performance.md
status	maintained
publication	reviewed

PRIK

Python Runtime Interop Kit.

Turn Fortran into natural Python APIs.

Build clean, importable native extensions from supported Fortran without writing low-level binding code. PRIK preserves modules, derived types, arrays, and native behavior, and generates an editable .pyi contract so you can shape the Python API.

Project status: Alpha (0.1.x). Core Fortran wrapper workflows are implemented and tested across supported compilers, but public APIs may still change before 1.0.

The complete example below builds with one command:

python3 -m prik points.f90 --out geometry

---

See it in action

Create points.f90:

module points
  implicit none

  type :: point
    real(8) :: x = 0.0d0
    real(8) :: y = 0.0d0
  end type point

contains

  subroutine move(item, dx, dy)
    type(point), intent(inout) :: item
    real(8), intent(in) :: dx, dy
    item%x = item%x + dx
    item%y = item%y + dy
  end subroutine move

  real(8) function norm_squared(item) result(value)
    type(point), intent(in) :: item
    value = item%x * item%x + item%y * item%y
  end function norm_squared

end module points

Generated Python API:

import numpy as np
import geometry.points as points

item = points.point(x=np.float64(3.0), y=np.float64(4.0))
points.move(item, np.float64(1.0), np.float64(-2.0))

print(item.x, item.y)             # 4.0 2.0
print(points.norm_squared(item))  # 20.0

No manual bindings are required. From this source, PRIK creates a Python namespace, a class with accessible fields, a mutating procedure, and a function.

Want a different Python API? Edit the generated .pyi contract to rename or hide exports, flatten namespaces, define constructors and methods, or create overloads. The contract guide shows the available edits.

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How it works

1. Write standard Fortran.
2. Run prik on the source.
3. Import the generated native extension.
4. Optionally edit the generated .pyi contract to shape the Python API.

No manual binding code or low-level boilerplate.

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Key Features

• Fortran modules exposed as Python namespaces and derived types as classes
• NumPy arrays with explicit dtype, shape, and layout checks
• Allocatable and pointer arrays with explicit lifetime operations
• Immediate Python callbacks and overloaded interfaces
• Editable .pyi contracts and readable generated docstrings
• Early, clear errors when a boundary cannot be wrapped
• Low wrapper overhead measured against NumPy's f2py in a reproducible benchmark suite

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Measured Performance

Low wrapper overhead, measured against NumPy's f2py.

The latest published benchmark runs both tools against the same Fortran kernels through their normal generated interfaces. Results are machine-dependent; the detailed page records the complete environment and reproduction method.

Runtime-call performance — values above 1.0× mean PRIK is faster.

{ .prik-performance-chart }

Clean end-to-end build time — lower times are better.

{ .prik-performance-chart }

View the full results and methodology →

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Ready to wrap your Fortran code?

Getting Started Guide →{ .prik-primary-cta }