site/contents/learn-scopes.md
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----- content-type: "page" title: "Scopes" ----- {@ _defs_.md || 0 @} As explained in [Definitions](/learn-definitions), min uses lexical scoping to resolve symbols. A *scope* is an execution context (a symbol table really) that: * is created while a new quotation is being dequoted or a dictionary is created. * is destroyed after a quotation has been dequoted. * is attached to a dictionary. The main, root-level scope in min can be accessed using the {#link-operator||lang||ROOT#} symbol and it typically contains all symbols and sigils imported from all the standard library modules. The ROOT symbol pushes a module on the stack that references the ROOT scope: > %min-terminal% > [[/Users/h3rald/test]$](class:prompt) ROOT > { > <native> :! > <native> :!= > ... > <native> :xor > <native> :zip > ;module > } > %note% > Note > > <native> values cannot be retrieved using the {#link-operator||dict||dget#} operator. ## Accessing the current scope You can access the current scope using the {#link-operator||lang||scope#} operator, which pushes a module on the stack that references the current scope. Consider the following program: {} :innerscope ("This is a test" :test scope @myscope) -> myscope scope-symbols In this case: 1. A new variable called `innerscope` is defined on the ROOT scope. 2. A quotation is dequoted, but its scope is retrieved using the `scope` operator and bound to `innerscope`. 3. After the quotation is dequoted, myscope is accessed and its symbols (`test` in this case) are pushed on the stack using the {#link-operator||lang||scope-symbols#} operator. Note that scopes can only be accessed if they are bound to a dictionary, hence the `ROOT` and `scope` operators push a module on the stack, and a module is nothing but a typed dictionary. ## Dequoting a quotation within the context of a specific scope The {#link-operator||lang||with#} operator can be used to dequote a quotation within a specific scope instead of the current one. Consider the following program, which leaves `2` on the stack: (4 2 minus) {'- :minus} with -> In this case, when `with` is pushed on the stack, it will dequote `(4 2 minus)`. Note that the symbol `minus` is defined in the dictionary that will be used by `with` as the current scope, so after `with` is pushed on the stack, the stack contents are: 4 2 (-) At this point, the {#link-operator||lang||dequote#} operator is pushed on the stack and the subtraction is executed leaving `2` on the stack. {#link-learn||control-flow||Control Flow#} |