On 8/12/2014 2:20 PM, Rustom Mody wrote:
On Tuesday, August 12, 2014 11:10:48 PM UTC+5:30, Neil D. Cerutti wrote:
Beginners are particularly poor, in relation to experts, at noticing the
applicability of idea, and at combining ideas together. Breaking things
into component parts has multiple benefits:
1. The applicability of individual ideas becomes obvious. It's one thing
to know about [].sort, and another thing to know when it's appropriate
to sort something.
2. The expert specifically shows how and why the ideas are combined.
This helps build the connection for the beginner, whose knowledge is not
stored as an expert stores it; i.e, in broad categories with multiple
connections; but as disorganized data with very few connections.
Nice!
And how do we lead the beginners towards expertise?
In a way functional programming is to programming creativity
what lego is to children's spatial creativity.
Specifically there are a bunch of pieces that need to fit:
1. Functional Programming: Nothing more than composing functions
[Maybe a bit simplistic but not unrealistic a defn]
2. Trying this out at the interpreter
3. Introspectable objects
Functional programming could be particularly hard to teach since it is
generally made up of numerous small units of work combined in a complex
way. This is precisely the formula for something that beginners will
find extremely challenging.
When functional programming is dumbed down enough for a beginner to be
able to grok it, the programming problems start to look really lame. It
needn't be that way, of course, but it takes a good deal of creativity
on the part of the instructor. If Factorial doesn't turn you on, you
might be screwed. ;)
Some things follow from this:
For the lego-game of playing with functions at the REPL to work and be
pleasant and rewarding:
1. functions should be non side-effecting; else same trials giving different
answers adds more confusion than understanding
2. They should be non-printing else:
def foo(x): return x+1
def bar(x): print x+1
look similar when trivially tried but compositionally are utterly different
In effect a printing function breaks the lego bricks
That may be so, but printing stuff to the screen is very natural to
people. I've downloaded Haskell a few times, but the knowledge that
getting input and writing output requires something mysterious called
gonads just frightens me.
[The P in the REPL is DRY enough that it does not usually need to be
repeated all over]
A good REPL does help a lot, though.
3. Abstractions (class instances) should be avoided in favor of
concrete data (lists, dicts, scalars) because they add undue mess at little
comprehension advantage. eg take the example of a regex match. It
returns some object and then we have to scratch our heads wondering
whats in the magic box. If instead of match, we use findall, the data
is manifest and obvious.
I'm with you on regex: match objects suck. That and escaping.
--
Neil Cerutti
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