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32 lines
1.5 KiB
Text
32 lines
1.5 KiB
Text
api Bool provides Bool.*, not, equal, notEqual
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## Either #True or #False.
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Bool := False, True
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## Returns #False when given #True, and vice versa.
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not : Bool -> Bool
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not = \bool ->
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case bool when
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False -> True
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True -> False
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## Returns #True if the two values are *structurally equal*, and #False otherwise.
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##
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## Structural equality works as follows:
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##
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## 1. #Int and #Float values are equal if their numbers are equal.
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## 2. Records are equal if all their fields are equal.
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## 3. Global tags are equal if they are the same tag, and also their contents (if any) are equal.
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## 4. Private tags are equal if they are the same tag, in the same module, and also their contents (if any) are equal.
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## 5. Collections (#String, #List, #Map, #Set, and #Bytes) are equal if they are the same length, and also all their corresponding elements are equal.
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## 6. All functions are considered equal. (So `Bool.not == Bool.not` will return #True, as you might expect, but also `Num.abs == Num.negate` will return #True, as you might not. This design is because function equality has been formally proven to be undecidable in the general case, and returning #True in all cases turns out to be mostly harmless - especially compared to alternative designs like crashing, making #equal inconvenient to use, and so on.)
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##
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## This is the same as the #== operator.
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eq : val, val -> Bool
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## Calls #eq on the given values, then calls #not on the result.
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##
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## This is the same as the #=/= operator.
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notEq : val, val -> Bool
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notEq = \left right ->
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not (equal left right)
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