Add initial draft of language specification #3618
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Cadence Benchstat comparisonThis branch with compared with the base branch onflow:master commit 4a2d406 Collapsed results for better readability
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turbolent
reviewed
Oct 18, 2024
| - **Allowed Characters**: | ||
| - Letters (a-z, A-Z) | ||
| - Digits (0-9) | ||
| - Special symbols used in operators and syntax, such as `+`, `-`, `*`, `/`, `=`, `{`, `}`, `(`, `)`, `[`, `]`, etc. |
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We might want to be exhaustive here
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| - **Unicode Support**: | ||
| - While the core syntax is based on ASCII characters, Unicode is fully supported in **string literals** and **comments**. | ||
| - Identifiers may include Unicode characters in the ranges of letters and numbers but should generally follow best practices for naming and clarity. |
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In general we can probably omit recommendations / best practices in this document
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| ### 2. Identifiers | ||
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| Identifiers in Cadence are used to name **variables**, **constants**, **functions**, **contracts**, **types**, and other user-defined entities. Identifiers must follow specific rules to ensure consistency and avoid conflicts with reserved keywords. |
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Contracts are also types, maybe remove. Just like above, we want to be exhaustive/specific, so also remove the remainder of the sentence.
Suggested change
| Identifiers in Cadence are used to name **variables**, **constants**, **functions**, **contracts**, **types**, and other user-defined entities. Identifiers must follow specific rules to ensure consistency and avoid conflicts with reserved keywords. | |
| Identifiers in Cadence are used to name **variables**, **constants**, **functions**, and **types**. Identifiers must follow specific rules to ensure consistency and avoid conflicts with reserved keywords. |
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| Identifiers in Cadence are used to name **variables**, **constants**, **functions**, **contracts**, **types**, and other user-defined entities. Identifiers must follow specific rules to ensure consistency and avoid conflicts with reserved keywords. | ||
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| - **Rules for Naming Identifiers**: |
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It might make sense to give the EBNF notation here
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| - **Special Identifiers**: | ||
| - Identifiers starting with an underscore (`_`) are typically used for private or internal entities. Although allowed, their use should follow common programming conventions. |
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This is mostly code style and not really part of the language specification
Suggested change
| - **Special Identifiers**: | |
| - Identifiers starting with an underscore (`_`) are typically used for private or internal entities. Although allowed, their use should follow common programming conventions. |
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| - **access**: Specifies the access control for the struct and its members (e.g., pub, access(contract), access(self)). | ||
| - **StructName**: The name of the struct. | ||
| - **Fields**: Declared with the let or var keywords. Constant fields (let) are immutable after initialization, while variable fields (var) can be modified after the struct is created. | ||
| - **Initializer**: The init function is responsible for initializing all fields in the struct. It ensures that each field is assigned a value before the struct is used. | ||
| - **Functions**: Structs can contain functions, which operate on their fields and are defined within the struct body. | ||
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| - **Example**: | ||
| ```cadence | ||
| pub struct User { | ||
| pub let id: Int | ||
| pub var name: String | ||
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| init(id: Int, name: String) { | ||
| self.id = id | ||
| self.name = name | ||
| } | ||
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| pub fun updateName(newName: String) { | ||
| self.name = newName | ||
| } | ||
| } | ||
| ``` |
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Note that in Cadence 1.0 the access specifiers pub, pub(set) and priv got removed. See "pub and priv Access Modifiers Got Removed" in https://github.com/onflow/cadence/releases/tag/v1.0.0
| - **Syntax**: | ||
| - The basic syntax for a resource declaration is as follows: | ||
| ```cadence | ||
| access(resource) resource ResourceName { |
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access(resource) is not a valid access modifier. See the implementation for a valid list: https://github.com/onflow/cadence/blob/master/ast/access.go
| let b: Int = 20 | ||
| ``` | ||
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| - **Unique Identifiers**: |
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Maybe describe this as "shadowing"
| var y = 10 // This will result in an error | ||
| ``` | ||
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| - **Redeclaration in Sub-scopes**: |
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Maybe reference scoping rules / and or move shadowing rules to scoping rules, given they are very closely related.
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| - **Rules for Storing Resources and Data**: | ||
| - Resources and data must be stored in well-defined paths under one of the storage categories (`storage`, `private`, or `public`). Resources are moved between accounts using explicit transactions and must be stored in the correct paths to ensure security and proper access control. | ||
| - Only the account owner can directly manipulate their `storage` paths. Public and private paths must use **capabilities** to grant or restrict access to external |
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Maybe mention here that Cadence uses lexical scoping (as opposed to e.g. dynamic scoping)
turbolent
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work towards: #3599
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