diff --git a/doc/manual/src/language/index.md b/doc/manual/src/language/index.md index c4b3abf75..a4b402f8b 100644 --- a/doc/manual/src/language/index.md +++ b/doc/manual/src/language/index.md @@ -1,13 +1,33 @@ # Nix Language -The Nix language is a pure, lazy, functional language. Purity -means that operations in the language don't have side-effects (for -instance, there is no variable assignment). Laziness means that -arguments to functions are evaluated only when they are needed. -Functional means that functions are “normal” values that can be passed -around and manipulated in interesting ways. The language is not a -full-featured, general purpose language. Its main job is to describe -packages, compositions of packages, and the variability within packages. +The Nix language is -This section presents the various features of the language. +- *domain-specific* + + It only exists for the Nix package manager: + to describe packages and configurations as well as their variants and compositions. + It is not intended for general purpose use. + +- *declarative* + + There is no notion of executing sequential steps. + Dependencies between operations are established only through data. + +- *pure* + + Values cannot change during computation. + Functions always produce the same output if their input does not change. + +- *functional* + + Functions are like any other value. + Functions can be assigned to names, taken as arguments, or returned by functions. + +- *lazy* + + Expressions are only evaluated when their value is needed. + +- *dynamically typed* + + Type errors are only detected when expressions are evaluated.