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Purity
Explanation of purity and impurity.
PurityA pure expression is an expression that has no side-effects. An expression is pure if and only if all sub-expressions are pure. Quotations and literals are always pure. A quotation may be impure if evaluated. A pure function is a function which consists of only pure expressions. A pure expression is referentially transparent. Pure functions have a type expressed as: (Consumption -> Production) where as impure functions have a type expressed as (Consumption ~> Production). A language is pure if only pure expressions can be expressed using it. The subset of Cat consisting of only Level0 and Level1 primitives is pure. |
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