Return a fixed-output derivation that fetches REF, a <cvs-reference> object. The output is expected to have recursive hash HASH of type HASH-ALGO (a symbol). Use NAME as the file name, or a generic name if #f.

Return the file name of the derivation INPUT refers to.

Read the derivation from DRV-PORT and return the corresponding <derivation> object. Call READ-DERIVATION-FROM-FILE to read derivations declared as inputs of the derivation being parsed.

Most of the time you'll want to use 'read-derivation-from-file', which caches things as appropriate and is thus more efficient.

Return a one-argument procedure that, when passed a store file name, returns a 'substitutable?' if it's substitutable and #f otherwise.

The returned procedure knows about all substitutes for all the derivation inputs or derivations listed in INPUTS-OR-DRV, *except* those that are already valid (that is, it won't bother checking whether an item is substitutable if it's already on disk); it also knows about their prerequisites, unless they are themselves substitutable.

Creating a single oracle (thus making a single 'substitutable-path-info' call) and reusing it is much more efficient than calling 'has-substitutes?' or similar repeatedly, because it avoids the costs associated with launching the substituter many times.

Given MAPPING, a list of pairs of derivations, return a derivation based on DRV where all the 'car's of MAPPING have been replaced by its 'cdr's, recursively.

Return the hash of DRV, modulo its fixed-output inputs, as a bytevector.

Perform a breadth-first traversal of INPUTS, calling PROC on each input with the current result, starting from SEED. Skip recursion on inputs that match CUT?.

Return true if DRV can be offloaded, false otherwise.

Return the list of name/path pairs of the outputs of DRV.