lazy monads... "fib monad"

monadexperiement-unfinished.js

var list_monad = {}

// a -> [a]
list_monad.unit = function (value) {
    return [value]
}

// (a -> [a]) -> ([a] -> [a])
list_monad.bind = function(fn) {
    return function(values) {
        return values.map(fn)
    }
}

var compose =  function(f,g) {
    return function(v) { return  f(g(v)) }
}


var _unit = list_monad.unit
var _bind = list_monad.bind
var _compose = compose

// m >>= fn
var fn = function(elem) {
    return elem * 2;
}
var pp = console.log
pp(_bind(fn)(_unit(1)))
pp(_bind(fn)((_bind(fn)(_unit(1)))))

pp(_bind(fn)([10,2]))
pp(_bind(fn)((_bind(fn)([10,2]))))


var unit = function(x,y) {
    y = y || 1;
    x = x || 0;
    return [x,y]
}

var bind = function(afn) {
    return function(value) {
        var x = value[0]
        var y = value[1];
        return [y, x+y]
        
    }
}

pp(unit()[0])
pp(bind()(unit())[0])
pp(bind()(bind()(unit()))[0])

function pipe(initval, functions) {
    //ifunction = initval
    val = initval;
    for(var i = 0; i < functions.length ;i++) {
        val = bind(functions[i])(val)
    }
    pp(">>",val[0])
}
var fn = function(v){console.log("-->",v);}
pipe(unit(), [])
pipe(unit(), [fn ])
pipe(unit(), [fn, fn ])
pipe(unit(), [fn, fn, fn ])
pipe(unit(), [fn, fn, fn, fn ])
//console.log(results)
/*
~/source/nodejs$ node lazyfib.js
[ 2 ]
[ 4 ]
[ 20, 4 ]
[ 40, 8 ]
0
1
1
>> 0
>> 1
>> 1
>> 2
>> 3
*/