Smalltalk Prime Generator with a connected list not working - linked-list

Question

Been trying to debug this code for a while but I can't seem to understand the problem at hand.
The program that I'm making is a Smalltalk program that has to use a connected list with nodes to generate prime numbers.
The problem at hand apparently is this line:
But I can't seem to figure out what would need to be changed in it. As it seems correct to me. And the Smalltalk error codes are certainly not helping much:
I Should note that I am using an online IDE (jdoodle.com) for coding this.
This one in particular: https://www.jdoodle.com/execute-smalltalk-online/
If you drop the given code in https://www.jdoodle.com/execute-smalltalk-online/ You should get the same error.
The full code:
Object subclass: #Node
instanceVariableNames: 'value next'
classVariableNames: ''
poolDictionaries: ''
category: 'MyApplication'
!Node methodsFor: 'initialization'!
init
"Initialize a new node"
super init.
value := nil.
next := nil.
^self
! !
!Node methodsFor: 'accessing'!
value
"Return the node's value"
^value
! !
!Node methodsFor: 'accessing'!
next
"Return the next node in the list"
^next
! !
!Node methodsFor: 'accessing'!
setValue: anObject
"Set the node's value"
value := anObject
! !
!Node methodsFor: 'accessing'!
setNext: aNode
"Set the next node in the list"
next := aNode
! !
Object subclass: #ConnectedList
instanceVariableNames: 'head tail'
classVariableNames: ''
poolDictionaries: ''
category: 'MyApplication'
!ConnectedList methodsFor: 'initialization'!
init
"Initialize a new connected list"
super init.
head := nil.
tail := nil.
^self
! !
!ConnectedList methodsFor: 'accessing'!
head
"Return the head of the list"
^head
! !
!ConnectedList methodsFor: 'accessing'!
tail
"Return the tail of the list"
^tail
! !
!ConnectedList methodsFor: 'accessing'!
isEmpty
"Return true if the list is empty, false otherwise"
^head isNil
! !
!ConnectedList methodsFor: 'adding'!
add: anObject
"Add an object to the list"
| newNode |
newNode := Node new.
newNode setValue: anObject.
newNode setNext: nil.
"newNode := Node value: anObject next: nil." "Maybe we need to initialize a node first and then add values?"
"If the list is empty, set the head and tail to the new node"
head isNil
ifTrue: [
head := newNode.
tail := newNode.
]
"Otherwise, add the new node to the end of the list"
ifFalse: [
tail setNext: newNode. "maybe?: tail setNext: newNode | tail next: newNode"
tail := newNode.
].
^self
! !
Object subclass: #PrimesGenerator
instanceVariableNames: 'primes'
classVariableNames: ''
poolDictionaries: ''
category: 'MyApp-PrimesGenerator'
!PrimesGenerator class methodsFor: 'instance creation'!
"Create a new PrimesGenerator object"
new
"Initialize the object and return it"
^self basicNew initialize
! !
!PrimesGenerator methodsFor: 'initialization'!
initialize
"Create a new ConnectedList to hold the prime numbers"
primes := ConnectedList new.
"Seed the list with the first prime number, 2"
primes add: 2.
^self
! !
!PrimesGenerator methodsFor: 'generating primes'!
next
"Return the next prime number in the sequence"
| value |
value := 3.
"Continuously generate new values and check if they are prime. If not,
generate the next value until a prime number is found"
[ primes do: [ :each | value \\ each = 0 ifTrue: [ ^self next ] ] ] whileTrue.
"Add the new prime number to the list"
primes add: value.
^value
! !
"Create a new PrimesGenerator object"
generator := PrimesGenerator new.
"Generate the first 5 prime numbers"
1 to: 5 do: [ :i |
Transcript show: generator next; cr.
].
The expected result of this code would be that it writes out the prime numbers as follows
2
3
5
7
11
Does anyone have an idea how to fix this?

Answer 1

Actually looks pretty good for a first attempt.
A little more work should get you going.
Your ConnectedList does not have a new method.
Your ConnectedList does not have an initialize method.
Your Node class is missing the same two methods.
The #whileTrue loop in your #next method is messed up.
It should look something like this:
[ aBooleanExpression
] whileTrue.
Yours looks more like this:
[ [someCode which does not result in a boolean].
] whileTrue.
5. Your ConnectedList does not have a #do: method.
You'll need it to evaluate a1block parameter
with each of the nodes in the ConnectedList,
It should be something similar to this:
>>do: a1block
node := head.
[ node isNil
] whileFalse:
[ a1block value: node.
node := node next
]