ty: A Go repository from BurntSushi

Package ty provides utilities for writing type parametric functions with run time type safety.

This package contains two sub-packages fun and data which define some potentially useful functions and abstractions using the type checker in this package.

Requirements

Go tip (or 1.1 when it's released) is required. This package will not work with Go 1.0.x or earlier.

The very foundation of this package only recently became possible with the addition of 3 new functions in the standard library reflect package: SliceOf, MapOf and ChanOf. In particular, it provides the ability to dynamically construct types at run time from component types.

Further extensions to this package can be made if similar functions are added for structs and functions(?).

Installation

go get github.com/BurntSushi/ty
go get github.com/BurntSushi/ty/fun

Examples

Squaring each integer in a slice:

square := func(x int) int { return x * x }
nums := []int{1, 2, 3, 4, 5}
squares := Map(square, nums).([]int)

Reversing any slice:

slice := []string{"a", "b", "c"}
reversed := Reverse(slice).([]string)

Sorting any slice:

// Sort a slice of structs with first class functions.
type Album struct {
  Title string
  Year int
}
albums := []Album{
  {"Born to Run", 1975},
  {"WIESS",       1973},
  {"Darkness",    1978},
  {"Greetings",   1973},
}

less := func(a, b Album) bool { return a.Year < b.Year },
sorted := QuickSort(less, albums).([]Album)

Parallel map:

// Compute the prime factorization concurrently
// for every integer in [1000, 10000].
primeFactors := func(n int) []int { // compute prime factors }
factors := ParMap(primeFactors, Range(1000, 10001)).([]int)

Asynchronous channel without a fixed size buffer:

s, r := AsyncChan(new(chan int))
send, recv := s.(chan<- int), r.(<-chan int)

// Send as much as you want.
for i := 0; i < 100; i++ {
  s <- i
}
close(s)
for i := range recv {
  // do something with `i`
}

Shuffle any slice in place:

jumbleMe := []string{"The", "quick", "brown", "fox"}
Shuffle(jumbleMe)

Function memoization:

// Memoizing a recursive function like `fibonacci`.
// Write it like normal:
var fib func(n int64) int64
fib = func(n int64) int64 {
  switch n {
  case 0:
    return 0
  case 1:
    return 1
  }
  return fib(n - 1) + fib(n - 2)
}

// And wrap it with `Memo`.
fib = Memo(fib).(func(int64) int64)

// Will keep your CPU busy for a long time
// without memoization.
fmt.Println(fib(80))