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https://github.com/xyproto/purefunction
Given a Go source code file, find all known pure functions
https://github.com/xyproto/purefunction
optimization-tools static-code-analysis
Last synced: about 1 month ago
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Given a Go source code file, find all known pure functions
- Host: GitHub
- URL: https://github.com/xyproto/purefunction
- Owner: xyproto
- License: bsd-3-clause
- Created: 2018-09-21T13:01:21.000Z (about 6 years ago)
- Default Branch: main
- Last Pushed: 2022-03-28T11:24:52.000Z (over 2 years ago)
- Last Synced: 2024-10-05T15:25:10.307Z (about 2 months ago)
- Topics: optimization-tools, static-code-analysis
- Language: Go
- Homepage:
- Size: 1.23 MB
- Stars: 6
- Watchers: 3
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# purefunction [](http://godoc.org/github.com/xyproto/purefunction) [](https://raw.githubusercontent.com/xyproto/purefunction/master/LICENSE) [](https://goreportcard.com/report/github.com/xyproto/purefunction)
Given a Go source file, find the names of all functions that are known to be pure.
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 or 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).
### Examples of pure functions
Example of a pure function:
```go
func add(a, b int) int {
return a + b
}
```
Another example of a pure function (even though it is a "method"):
```go
func (c *Config) Add(a, b int) int {
return a + b
}
```
### Features and limitations
* Functions are filtered out if they have non-pure indicators. The ones that are left are considered pure.
* Functions that read from a file, read from the keyboard, uses randomness or the system time are not pure, but may be detected as such.
### Approach
* Uses [`go/ast`](http://golang.org/pkg/go/ast) extensively.
### Memoization
Pure functions, like the `fibonacci` function, has great potential for optimization by memoization.
Benchmark output for "fibonacci" vs "memoized fibonacci":
```
goos: linux
goarch: amd64
pkg: github.com/xyproto/purefunction/example
BenchmarkFib10-8 30586 38894 ns/op
BenchmarkFibMemoized-8 84117813 14.2 ns/op
PASS
ok github.com/xyproto/purefunction/example 2.798s
```
See issue #1.
### Requirements
* Go 1.10 or later.
### General info
* Version: 1.0.3
* License: BSD-3
* Author: Alexander F. Rødseth <[email protected]>