Improve compile time error for #sort(&block : T, T -> U)
#14693
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src/array.cr
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| @@ -1680,7 +1680,7 @@ class Array(T) | |||
| # Raises `ArgumentError` if for any two elements the block returns `nil`. | |||
| def unstable_sort(&block : T, T -> U) : Array(T) forall U | |||
| {% unless U <= Int32? %} | |||
| {% raise "Expected block to return Int32 or Nil, not #{U}" %} | |||
| {% raise "Expected block to return Int32 or Nil, not #{U} (see Comparable#<=>)" %} | |||
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I don't know if stdlib has a policy on tone for error messages or not, so please forgive the suggestion if I'm out of step. I had been planning to submit a pull like this, but admittedly wouldn't have been as comprehensive as you have been here.
Looking at the docs for Comparable#<=>, I'm not sure it would have actually helped me get what I wanted out of the situation. What do you think about an error message which is a little more prescriptive? Something like "did you mean to use #sort_by?" (or unstable_sort_by, sort_by!, etc).
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I'd agree we could be a bit more elaborate.
WDYT about this?
| {% raise "Expected block to return Int32 or Nil, not #{U} (see Comparable#<=>)" %} | |
| {% raise "Expected block to return Int32 or Nil, not #{U}.\nThe block is supposed to be a custom comparison operation, compatible with `Comparable#<=>`.\nDid you mean to use `#sort_by?`" %} |
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Do multiline compiler errors render well?
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Yeah, that should be fine.
$ crystal eval '{% raise "Expected block to return Int32 or Nil.\nThe block is supposed to be a custom comparison operation, compatible with `Comparable#<=>`.\nDid you mean to use `#sort_by?`" %}'
Showing last frame. Use --error-trace for full trace.
error in line 1
Error: Expected block to return Int32 or Nil, not.
The block is supposed to be a custom comparison operation, compatible with `Comparable#<=>`.
Did you mean to use `#sort_by?`
straight-shoota
changed the title
sort#sort(&block : T, T -> U) with mismatching U
straight-shoota
changed the title
#sort(&block : T, T -> U) with mismatching U#sort(&block : T, T -> U)
Little improvement to reference
Comparable#<=>insortoperations. Ref: https://forum.crystal-lang.org/t/sort-by-time/6918/1