Return a <derivation-input> for the OUTPUTS of DRV.

Read the derivation from PATH (`/gnu/store/xxx.drv'), and return the store path of its output OUTPUT.

Return the store path of its output OUTPUT. Raise a '&derivation-missing-output-error' condition if OUTPUT is not an output of DRV.

Read the derivation from PATH (`/gnu/store/xxx.drv'), and return the list of name/path pairs of its outputs.

Return the base name of DRV.

Read the derivation in FILE, a '.drv' file, and return the corresponding <derivation> object.

Return #t if DRV is a fixed-output derivation, such as the result of a download with a fixed hash (aka. `fetchurl').

Given MAPPING, a list of pairs of derivations, return a derivation based on DRV where all the 'car's of MAPPING have been replaced by its 'cdr's, recursively.

Build a derivation with the given arguments, and return the resulting <derivation> object. When HASH and HASH-ALGO are given, a fixed-output derivation is created---i.e., one whose result is known in advance, such as a file download. If, in addition, RECURSIVE? is true, then that fixed output may be an executable file or a directory and HASH must be the hash of an archive containing this output.

When REFERENCES-GRAPHS is true, it must be a list of file name/store path pairs. In that case, the reference graph of each store path is exported in the build environment in the corresponding file, in a simple text format.

When ALLOWED-REFERENCES is true, it must be a list of store items or outputs that the derivation's outputs may refer to. Likewise, DISALLOWED-REFERENCES, if true, must be a list of things the outputs may not refer to.

When LEAKED-ENV-VARS is true, it must be a list of strings denoting environment variables that are allowed to "leak" from the daemon's environment to the build environment. This is only applicable to fixed-output derivations--i.e., when HASH is true. The main use is to allow variables such as "http_proxy" to be passed to derivations that download files.

When LOCAL-BUILD? is true, declare that the derivation is not a good candidate for offloading and should rather be built locally. This is the case for small derivations where the costs of data transfers would outweigh the benefits.

When SUBSTITUTABLE? is false, declare that substitutes of the derivation's output should not be used.

PROPERTIES must be an association list describing "properties" of the derivation. It is kept as-is, uninterpreted, in the derivation.

Return the file name of the derivation INPUT refers to.

Return the list of output paths corresponding to INPUT, a <derivation-input>.

Return true if DRV can be offloaded, false otherwise.