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Hello, world!

Python

print "Hello, world!"

Chicken

(print "Hello, world!")

Definitions, assignment and bindings

Python

Python has only one operator for both assignments and definitions of variables (=).

a = 0

Chicken

Defining a variable:

(define a 0)

Assigning a variable a value:

(set! a 0)

PS: Chicken automatically defines a global variable when a variable is set without being defined.

Binding a value to a variable:

(let ((a 0))
   a)

Strings

Concatenating

Python

a = "1" + "2"
a = "".join(["1", "2"])

Chicken

(string-append "1" "2")
(conc "1" 2)
(string-intersperse '("1" "2") "")

Spliting a string

Python

"this is a string".split()

Chicken

(string-split "this is a string")

File I/O

Reading the contents of a file and returning a string

Python

open("my-file.txt").read()

Chicken

(read-all "my-file.txt")

read-all is defined in Unit utils.

Reading the contents of a file and returning a list of lines

Python

open("my-file.txt").readlines()

Chicken

(read-lines "my-file.txt")

read-lines is defined in Unit utils.

Conditionals

Single condition

Python

result = None
if 1 < 2:
    result = "yes"
else:
    result = "no"

Chicken

(if (< 1 2) "yes" "no")

PS: in Scheme, the result of the evaluation of an if form is passed to its continuation.

Multiple conditions

Python

result = None
if 1 < 2:
    result = "1 < 2"
elif 1 > 2:
    result = "1 > 2"
else:
    result = "1 = 2"

Chicken

(cond ((< 1 2) "1 < 2")
      ((> 1 2) "1 > 2")
      (else "1 = 2"))

PS: in Scheme, the result of the evaluation of a cond form is passed to its continuation.

Iteration

Iterating through and printing the elements of a list

Python

l = [1, 2, 3, 4]
for i in l:
    print i

Chicken

(define l '(1 2 3 4))
(for-each print l)

Applying a procedure/function to each item of a list

Python

l = [1, 2, 3, 4]

def add10(n):
    return n + 10

[ add10(i) for i in l ]

Chicken

(define l '(1 2 3 4))

(define (add10 n) (+ n 10))

(map add10 l)