nix-repl> :l <nixpkgs>
Added 8100 variables.

nix-repl> simple = derivation { name = "simple"; builder = "${bash}/bin/bash"; args = [ ./simple_builder.sh ]; gcc = stdenv.cc; coreutils = coreutils; src = ./simple.c; system = builtins.currentSystem; }

nix-repl> :b simple
these derivations will be built:
  /nix/store/fi3ygvhbkgpqzgp0if5j2hynf3jay6l0-simple.drv
building path(s) ‘/nix/store/80svrhb6anr25lic6l0xsmcwa0gkr6ki-simple’
/nix/store/4wpv68jkvw9nbnh4qcblnfvdfnn74kbn-simple_builder.sh: line 3: gcc: command not found
builder for ‘/nix/store/fi3ygvhbkgpqzgp0if5j2hynf3jay6l0-simple.drv’ failed with exit code 127
error: build of ‘/nix/store/fi3ygvhbkgpqzgp0if5j2hynf3jay6l0-simple.drv’ failed

nix-repl>