DashKite Generic

Generic functions


Examples

$3

``coffeescript
import { memoize } from "@dashkite/joy/function"

fib = Generic.make "fib", "Fibonacci sequence"
.define [ gte 0 ], memoize ( n ) -> ( fib n - 1 ) + ( fib n - 2 )
.define [ eq 1 ], -> 1
.define [ eq 2 ], -> 1

assert.equal 5, fib 5
assert.throws -> fib 0
`

$3

`coffeescript
import { has } from "@dashkite/joy/object"

length = Generic.make "size", "Return the size of a value"
# based on interface
.define [ has "length" ], ( value ) -> value.length
# based on type
.define [ Object ], ( object ) -> ( Object.keys object ).length
.define [ Set ], ( set ) -> set.values().length

assert.equal 5, size "hello"
assert.equal 3, size [ 1..3 ]
assert.equal 2, size x: 0, y: 0
assert.equal 1, size new Set [ true ]
`

$3

`coffeescript
class Adder
constructor: ( @total = 0 ) ->
add: ( f = Generic.make "Adder::add" )
.define [ Number ], ( operand ) ->
@total += operand
@

assert.equal 12,
( new Adder )
.add 5
.add 7
.total
``