SRFI 1

Map a function on a list and append elements

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8
  (if (equal?
       (append-map (lambda (x) (list (* 2 x) (* x x))) '(<input>))
       '(<output>))
    65
    66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

input	output
1	2 1
1 2	2 1 4 4
1 2 3	2 1 4 4 6 9

Delete duplicates in a list

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (delete-duplicates '(<input>)) '(<output>)) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

input	output
1	1
1 1	1
1 1 2 2	1 2
1 2 1 2	1 2
1 2 1 3 3 2 3	1 2 3

Filter a list

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (filter odd? '(<input>)) '(<output>)) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

input	output
1	1
2
1 2	1
1 2 3	1 3
1 2 3 4	1 3
1 2 3 4 5 6	1 3 5

Reduce a list

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (fold + 0 '(<elements>)) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	output
	0
1	1
1 2	3
1 2 3	6

Fold a list from right

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (fold-right + 0 '(<elements>)) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	output
	0
1	1
1 2	3
1 2 3	6

Enumerate numbers

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (iota <arguments>) '(<elements>)) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

arguments	elements
0
1	0
2	0 1
3	0 1 2
1 1	1
1 2	2
3 5	5 6 7
3 5 2	5 7 9

Find an element

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (eq? (find even? '(<elements>)) <element>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	element
	#f
1	#f
1 3	#f
2	2
1 2	2
1 3 4 5	4

Find a tail of a list

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (find-tail even? '(<elements>)) <value>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	value
	#f
1	#f
1 3	#f
2	’(2)
1 2	’(2)
1 3 4 5	’(4 5)

Check if any element meets a condition

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (any even? '(<elements>)) <value>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	value
	#f
1	#f
1 3	#f
2	#t
1 2	#t
1 2 3 4 5	#t

Check if every element meets a condition

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (every even? '(<elements>)) <value>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	value
	#t
1	#f
1 3	#f
2	#t
1 2	#f
2 4 6	#t
2 4 5	#f
1 2 3 4 5	#f

Calculate an index of an element

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (list-index <predicate> <lists>) <index>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

predicate	lists	index
even?	’()	#f
even?	’(1)	#f
even?	’(1 3)	#f
even?	’(2)	0
even?	’(1 2)	1
even?	’(1 2 3)	1
even?	’(1 3 2)	2
=	’(0 2) ’(1 2 3)	1
=	’(2 1 3) ’(1 2 3)	2

Reduce numbers

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (reduce + 42 '(<elements>)) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	output
	42
0	0
1	1
1 2	3
1 2 3	6

Reduce numbers from right

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (equal? (reduce-right + 42 '(<elements>)) <output>) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Examples

elements	output
	42
0	0
1	1
1 2	3
1 2 3	6

Get the fourth tail of a list

Given a file named “main.scm” with:

(import (scheme base) (srfi 1))

(write-u8 (if (eq? (cddddr '(x x x x)) '()) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.