Functional Programming

notes from the field.

In general,

new_collection = collection.map(function)

is a short-cut for:

new_collection[]
for (element in collection)
 new_collection[] += function(element)

And:

new_collection = collection.filter(function)

is a short-cut for:

new_collection[]
for (element in collection):
  if function(element):
    new_collection[] += function(element)

this

doubled = [1, 2, 3, 4, 5].map(x => x * 2)

is equivalent to:

doubled[]
for (x in [1, 2, 3, 4, 5]):
  doubled[] += x * 2

that