diff --git a/public/collection-functions b/public/collection-functions deleted file mode 100644 index 638293f..0000000 --- a/public/collection-functions +++ /dev/null @@ -1,369 +0,0 @@ - - - - - Go by Example: Collection Functions - - - - -
-

Go by Example: Collection Functions

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-

We often need our programs to perform operations on -collections of data, like selecting all items that -satisfy a given predicate or mapping all items to a new -collection with a custom function.

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-

In some languages it’s idiomatic to use generic -data structures and algorithms. Go does not support -generics; in Go it’s common to provide collection -functions if and when they are specifically needed for -your program and data types.

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-

Here are some example collection functions for slices -of strings. You can use these examples to build your -own functions. Note that in some cases it may be -clearest to just inline the collection-manipulating -code directly, instead of creating and calling a -helper function.

- - 		- - -
- - - - 
package main
-
-
- - - - 
import (
-    "fmt"
-    "strings"
-)
-
-
-

Index returns the first index of the target string t, or --1 if no match is found.

- - 		- - 
-func Index(vs []string, t string) int {
-    for i, v := range vs {
-        if v == t {
-            return i
-        }
-    }
-    return -1
-}
-
-
-

Include returns true if the target string t is in the -slice.

- - 		- - 
-func Include(vs []string, t string) bool {
-    return Index(vs, t) >= 0
-}
-
-
-

Any returns true if one of the strings in the slice -satisfies the predicate f.

- - 		- - 
-func Any(vs []string, f func(string) bool) bool {
-    for _, v := range vs {
-        if f(v) {
-            return true
-        }
-    }
-    return false
-}
-
-
-

All returns true if all of the strings in the slice -satisfy the predicate f.

- - 		- - 
-func All(vs []string, f func(string) bool) bool {
-    for _, v := range vs {
-        if !f(v) {
-            return false
-        }
-    }
-    return true
-}
-
-
-

Filter returns a new slice containing all strings in the -slice that satisfy the predicate f.

- - 		- - 
-func Filter(vs []string, f func(string) bool) []string {
-    vsf := make([]string, 0)
-    for _, v := range vs {
-        if f(v) {
-            vsf = append(vsf, v)
-        }
-    }
-    return vsf
-}
-
-
-

Map returns a new slice containing the results of applying -the function f to each string in the original slice.

- - 		- - 
-func Map(vs []string, f func(string) string) []string {
-    vsm := make([]string, len(vs))
-    for i, v := range vs {
-        vsm[i] = f(v)
-    }
-    return vsm
-}
-
-
- - - - 
func main() {
-
-
-

Here we try out our various collection functions.

- - 		- - 
-    var strs = []string{"peach", "apple", "pear", "plum"}
-
-
- - - - 
    fmt.Println(Index(strs, "pear"))
-
-
- - - - 
    fmt.Println(Include(strs, "grape"))
-
-
- - - - 
    fmt.Println(Any(strs, func(v string) bool {
-        return strings.HasPrefix(v, "p")
-    }))
-
-
- - - - 
    fmt.Println(All(strs, func(v string) bool {
-        return strings.HasPrefix(v, "p")
-    }))
-
-
- - - - 
    fmt.Println(Filter(strs, func(v string) bool {
-        return strings.Contains(v, "e")
-    }))
-
-
-

The above examples all used anonymous functions, -but you can also use named functions of the correct -type.

- - 		- - 
-    fmt.Println(Map(strs, strings.ToUpper))
-
-
- - - - 
}
-
-
- - - - - - - - -
- - - - 
$ go run collection-functions.go 
-2
-false
-true
-false
-[peach apple pear]
-[PEACH APPLE PEAR PLUM]
-
- - -

- Next example: String Functions. -

- - -

- by Mark McGranaghan and Eli Bendersky | source | license -

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