purefunction

README

purefunction

Given a Go source file, find the names of all functions that are known to be pure.

Pure functions, like the fibonacci function, has great potential for optimization by memoization.

Uses go/ast extensively.

A "pure function" for this module is, a function that:

• Only calls functions that are known to be pure, if any.
• Does not read or write to any global variables.
• Does not have pointers of slices as function arguments.
• Does not read or write to any memory location using pointers.
• Ideally: Always returns the same answer, given the same input, but this is hard to test for (ref. halting problem).

Example of a pure function:

func add(a, b int) int {
    return a + b
}

Functions are filtered out if they have non-pure indicators. The ones that are left are considered pure. There may be false negatives, but not false positives.

General info

• Version: 1.0.0
• License: MIT
• Author: Alexander F. Rødseth <xyproto@archlinux.org>

Documentation

Index

• Variables
• func PureFunctions(filename string) ([]string, error)
• func SetVerbose(verbose bool)

Examples

• PureFunctions

Variables

var Verbose bool

Verbose can be set to true for output to stdout while processing source files

Functions

func PureFunctions

func PureFunctions(filename string) ([]string, error)

PureFunctions returns a slice with the function names that are considered pure

Example

filename := "test/main.go"
pureFunctions, err := PureFunctions(filename)
if err != nil {
	log.Fatalln(err)
}
fmt.Printf("Pure functions in %s:\n", filename)
sort.Strings(pureFunctions)
for _, name := range pureFunctions {
	fmt.Println(name)
}

Output:

Pure functions in test/main.go:
add
add2
mul
mul3

func SetVerbose

func SetVerbose(verbose bool)

SetVerbose can be used for enabling or disabling verbose output to stdout