F# Generic Constraints Table Excludes type-parameter

[kroppt]

The main part of the syntax is listed as:

type-parameter-list when constraint1 [ and constraint2]

The following table is listed on the page for the constraints:

Constraint	Syntax
Type Constraint	type-parameter :> type
Null Constraint	type-parameter : null
Explicit Member Constraint	[(]type-parameter [or ... or type-parameter)] : (member-signature)
Constructor Constraint	type-parameter : ( new : unit -> 'a )
Value Type Constraint	: struct
Reference Type Constraint	: not struct
Enumeration Type Constraint	: enum<underlying-type>
Delegate Constraint	: delegate<tuple-parameter-type, return-type>
Comparison Constraint	: comparison
Equality Constraint	: equality
Unmanaged Constraint	: unmanaged

Several of these exclude type-parameter. However, when I tested it with .NET 6, I found that it was actually required.

Consider the Comparison Constraint constraint.

❌ The following code does not compile:

let function1<'a when : comparison> = ()

✔️ The following code does compile:

let function1<'a when 'a: comparison> = ()

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• ID: 10e577e7-ce52-aa95-c2cc-b7c542af6f1b
• Version Independent ID: 7a1e9fb2-e1fb-04f2-2db5-b74b00d9c620
• Content: Constraints - F#
• Content Source: docs/fsharp/language-reference/generics/constraints.md
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• Microsoft Alias: dotnetcontent