with { inherit (import ./lists.nix) deepSeqList; inherit (import ./attrsets.nix) deepSeqAttrs; }; rec { # Identity function. id = x: x; # Constant function. const = x: y: x; # Named versions corresponding to some builtin operators. concat = x: y: x ++ y; or = x: y: x || y; and = x: y: x && y; mergeAttrs = x: y: x // y; # Take a function and evaluate it with its own returned value. fix = f: let result = f result; in result; # Flip the order of the arguments of a binary function. flip = f: a: b: f b a; # `seq x y' evaluates x, then returns y. That is, it forces strict # evaluation of its first argument. seq = x: y: if x == null then y else y; # Like `seq', but recurses into lists and attribute sets to force evaluation # of all list elements/attributes. deepSeq = x: y: if builtins.isList x then deepSeqList x y else if builtins.isAttrs x then deepSeqAttrs x y else seq x y; # Pull in some builtins not included elsewhere. inherit (builtins) pathExists readFile isBool isFunction isInt add sub lessThan; # Return the Nixpkgs version number. nixpkgsVersion = let suffixFile = ../.version-suffix; in readFile ../.version + (if pathExists suffixFile then readFile suffixFile else "pre-git"); # Whether we're being called by nix-shell. This is useful to inNixShell = builtins.getEnv "IN_NIX_SHELL" == "1"; }