Ashley Davis (Jul 11 2024 at 22:09): Ashley Davis (Jul 11 2024 at 22:09):I'm working towards adding the next test for my getNextRow function.
The code I need to add next means adding some fields to my record type. Previously it was just an empty record type:
GalleryItem : {
}
Now I've added the fields I need:
GalleryItem : {
width : Int U32,
height : Int U32,
headings : List Str,
}
I created a helper function that I can use in my tests to produce a default gallery item (not sure if my syntax is quite right here):
# Makes a gallery item for testing.
makeDefaultItem : _ -> GalleryItem
makeDefaultItem = \_ -> {
width: 10,
height: 20,
headings: []
}
Now I use that function to create some lists to pass into my function for testing:
# No items left returns current row.
expect
currentRowItems = [makeDefaultItem, makeDefaultItem, makeDefaultItem]
removedItems = [makeDefaultItem, makeDefaultItem]
headings = ["a", "b"]
out = getNextRow [] 10 21 currentRowItems 12 removedItems headings
out == {
row: {
items: [{}, {}],
offsetY: 0,
width: 12,
height: 21,
headings,
},
removedItems,
remainingItems: []
}
My updated code results in multiple type mismatches, but I'm stuck on the first one:
── TYPE MISMATCH in Layout.roc ─────────────────────────────────────────────────
This 4th argument to getNextRow has an unexpected type:
73│ out = getNextRow [] 10 21 currentRowItems 12 removedItems headings
^^^^^^^^^^^^^^^
This currentRowItems value is a:
List (* -> GalleryItem)
But getNextRow needs its 4th argument to be:
List {
headings : List Str,
height : Int U32,
width : Int U32,
}
My feeling is that I have supplied what it needs, but the error tells me that the types are somehow wrong.
This is the type signature of getNextRow:
getNextRow : List GalleryItem, Int U32, Int U32, List GalleryItem, Int U32, List GalleryItem, List Str -> { row : LayoutRow, removedItems: List GalleryItem, remainingItems : List GalleryItem }
getNextRow = \items, galleryWidth, targetRowHeight, currentRowItems, width, removedItems, headings ->
Anyone know what's wrong here?
I've pushed full code with all the errors here: https://github.com/ashleydavis/book-of-examples/blob/main/gallery/roc/layout.roc
Brendan Hansknecht (Jul 11 2024 at 22:22):Int U32 should just be U32
Brendan Hansknecht (Jul 11 2024 at 22:22):Cause U32 is something like: U32 : Int Unsigned32
Richard Feldman (Jul 11 2024 at 22:30):I think we should consider special-casing that one
Richard Feldman (Jul 11 2024 at 22:30):things like Int I32
Ashley Davis (Jul 11 2024 at 22:32):I don't think that is it.
I'd already been using Int U32 in multiple places without a problem yet.
But I replaced "Int U32" with "U32" across the file and I still get the same error.
── TYPE MISMATCH in Layout.roc ─────────────────────────────────────────────────
This 4th argument to getNextRow has an unexpected type:
73│ out = getNextRow [] 10 21 currentRowItems 12 removedItems headings
^^^^^^^^^^^^^^^
This currentRowItems value is a:
List (* -> GalleryItem)
But getNextRow needs its 4th argument to be:
List {
headings : List Str,
height : U32,
width : U32,
}
Oh, wow, surprised that works. Let me look deeper
Brendan Hansknecht (Jul 11 2024 at 22:40):I think you need to be calling makeDefaultItem in lines like [makeDefaultItem, makeDefaultItem, makeDefaultItem]
Brendan Hansknecht (Jul 11 2024 at 22:40):[makeDefaultItem {}, makeDefaultItem {}, makeDefaultItem {}]
Brendan Hansknecht (Jul 11 2024 at 22:40):That or you need getNextRow to take a list of functions that generate GalleryItem
Brendan Hansknecht (Jul 11 2024 at 22:41):Though in this case, I would probably just change makeDefaultItem to defaultItem and make it not a function at all
Brendan Hansknecht (Jul 11 2024 at 22:41):defaultItem : GalleryItem
defaultItem = {
width: 10,
height: 20,
headings: []
}
Ashley Davis said:
I'd already been using
Int U32in multiple places without a problem yet.
that's very surprising! It shouldn't work :sweat_smile:
Richard Feldman (Jul 11 2024 at 23:58):do you happen to have a code example which uses Int 32 and works? I'd like to figure out what's going on with that haha
Ashley Davis (Jul 15 2024 at 21:41):Well I wasn 't doing any calculations with "Int U32" yet but it did compile and I was able to pass them into and out of a function.
Ashley Davis (Jul 15 2024 at 21:46):Brendan Hansknecht said:
Oh, wow, surprised that works. Let me look deeper
Hi @Brendan Hansknecht I tried making the change you suggested. What does it mean to add empty curly brackets onto a function call?
It does compile now which is good, but trying to figure out why latest test started failing:
── EXPECT FAILED in Layout.roc ─────────────────────────────────────────────────
This expectation failed:
68│> # No items left returns current row.
69│> expect
70│> currentRowItems = [makeDefaultItem {}, makeDefaultItem {}, makeDefaultItem {}]
71│> removedItems = [makeDefaultItem {}, makeDefaultItem {}]
72│> headings = ["a", "b"]
73│> out = getNextRow [] 10 21 currentRowItems 12 removedItems headings
74│> out == {
75│> row: {
76│> items: [{}, {}],
77│> offsetY: 0,
78│> width: 12,
79│> height: 21,
80│> headings,
81│> },
82│> removedItems,
83│> remainingItems: []
84│> }
When it failed, these variables had these values:
currentRowItems : List GalleryItem
currentRowItems = [{ headings: [], height: 20, width: 10 }, { headings: [], height: 20, width: 10 }, { headings: [], height: 20, width: 10 }]
removedItems : List GalleryItem
removedItems = [{ headings: [], height: 20, width: 10 }, { headings: [], height: 20, width: 10 }]
headings : List Str
headings = ["a", "b"]
out : {
remainingItems : List GalleryItem,
removedItems : List GalleryItem,
row : {
headings : List Str,
height : Int Unsigned32,
items : List {},
offsetY : Int Unsigned32,
width : Int Unsigned32,
},
}
out = { remainingItems: [], removedItems: [{ headings: [], height: 20, width: 10 }, { headings: [], height: 20, width: 10 }], row: { headings: ["a", "b"], height: 21, items: [{}, {}, {}], offsetY: 0, width: 12 } }
Also @Brendan Hansknecht I actually need makeDefaultItem to be a function because soon I want to add optional parameters to it configure it differently for different tests. It needs be a kind of constructor that gives you standard defaults when you don't supply them.
Ashley Davis (Jul 15 2024 at 21:52):@Richard Feldman the message for the failing test doesn't seem to compare actual results vs expected. I think it just prints out the actual results.
Ashley Davis (Jul 15 2024 at 21:54):I got it working (yay), but would have been easier if the failing test message shows the diff between actual and expected.
Brendan Hansknecht (Jul 15 2024 at 22:00):There is no such thing as a zero arg function in roc.
In fact, you can see the one arg for makeDefault, \_. In Roc, _ is a placeholder for ignored values.
Brendan Hansknecht (Jul 15 2024 at 22:00):You technically could pass anything into makeDefault since the value is ignored, but the standard ignored arg in roc is an empty record {}
Richard Feldman (Jul 15 2024 at 22:05):Ashley Davis said:
I got it working (yay), but would have been easier if the failing test message shows the diff between actual and expected.
yeah I'd like to do this! It's a project that nobody is working on at the moment, but if anyone is interested, I can give pointers on where to get started :big_smile:
Luke Boswell (Jul 15 2024 at 22:08):Before we forget, we should make an issue an link to that zulip chat. Didn't we talk about the diff somewhere recently?
Ashley Davis (Jul 15 2024 at 22:19):Luke Boswell said:
Before we forget, we should make an issue an link to that zulip chat. Didn't we talk about the diff somewhere recently?
I think this one: https://roc.zulipchat.com/#narrow/stream/231634-beginners/topic/Type.20mismatch.3A.20Do.20I.20need.20explicit.20typing.20here.3F
Luke Boswell (Jul 15 2024 at 22:58):I thought there was one where Richard posted with a diff view he proposed
Luke Boswell (Jul 15 2024 at 22:59):Yeah this one https://roc.zulipchat.com/#narrow/stream/304641-ideas/topic/diffs.20in.20error.20messages/near/450008154
Last updated: Jul 26 2025 at 12:14 UTC