POPL lecturer

[POPL lecturer @POPL_er]

@gagg_ARIN Claude Shannon's mouse that could learn:
https://t.co/KxOu5TRUep

[POPL lecturer @POPL_er]

@gagg_ARIN Check this out: https://t.co/t68hwIIWKe
#NoelSharkey #EthicalAI

[POPL lecturer @POPL_er]

The ILP 2019 call for papers is now public!
https://t.co/6lYaWKuDEO
#CfP #conference #AI #MachineLearning #Inductive_Logic_Programming #Plovdiv #Bulgaria

[POPL lecturer @POPL_er]

An AI dilemma to get you thinking about ARIN: https://t.co/A6L5n3Qeu0

[POPL lecturer @POPL_er]

For some people today's the day... to make their own object - from scratch (only using closures)! Imagine yourself at Xerox's Palo Alto research centre - what were they thinking?!

[POPL lecturer @POPL_er]

#lang racket
(define (revB lst part)
(if (null? lst) part
(revB (cdr lst) (cons (car lst) part))
)
)

(define (toprev lst)
(revB lst '()))

[POPL lecturer @POPL_er]

#lang racket
(define (rev lst)
(if (null? lst) lst
(append (rev (cdr lst)) (list (car lst)) )
)
)

(define (appendA x y)
(if (null? x) y
(cons (car x) (appendA (cdr x) y))
)
)

[POPL lecturer @POPL_er]

https://t.co/2dXBBiozj2

[POPL lecturer @POPL_er]

Solutions to POPL Week 2-3 practicals are on the VLE now.

[POPL lecturer @POPL_er]

; the example I discussed on Thu morning:
(define (loop name)
(begin
(newline)
(display '**)
(let ((response (read)))
(if (equal? response '(bye))
(print '(see you later))
(loop name)
)
)
)
)

[POPL lecturer @POPL_er]

In today's CARING practical, consider using (map proc lst) from last lecture to reimplement the procedures replace and many-replace. (You don't need to use map, but you'll need to reimplement those procedures.)

[POPL lecturer @POPL_er]

;Talking about special forms in Scheme:
> (display 'hello)
hello
> (* (+ 2 3) (+ 4 5))
45
> (begin (* 2 3) (* 4 5))
20
> (begin (display "I got this far!!") (* 4 5))
I got this far!!20
> (* 2 (begin (display "I got this far!!") (* 4 5)))
I got this far!!40
>

[POPL lecturer @POPL_er]

Code from the lecture:
#lang racket
(define (square x) (* x x))
(define (map proc lst)
(if (null? lst) '()
(cons (proc (car lst))
(map proc (cdr lst))
)
)
)

[POPL lecturer @POPL_er]

A little story about Sussman, Scheme and Python: https://t.co/x0B9xbsYpe

[POPL lecturer @POPL_er]

Here comes the full quote:
https://t.co/hFZygbqTmq

[POPL lecturer @POPL_er]

Indeed...!

[luke @LukeMoll_]

@POPL_er (define (length lst) (
if (null? lst) 0 (+ 1 (length(cdr lst)))
)

[POPL lecturer @POPL_er]

#badpunscompetition
;What does this say?
(define today (car (cdr yourlife)))

[POPL lecturer @POPL_er]

(length <a-list>) is built in Scheme. But you can write it easily using recursion: how?

[POPL lecturer @POPL_er]

; would this do?
(define (length lst)
(if (null? lst) 0
(+ 1 (length (cdr lst)))))