Couldn't find the language specification anywhere, it basically the Nix source? The repo's README refers to the Nix manual, but it seems incomplete. For example
tolist
bpmn
googlemock
rowdatabound
android-tv
eucalyptus
user-interaction
ghc-pkg
variable-assignment
ngx-editor
shell32
perfmon
restkit-0.20
installation
sas
google-auth-library-nodejs
google-civic-information-api
metrics-server
iif-function
pst
powerapps-component-framework
torrent
custom-selectors
azure-resource-manager
django-parler
revitpythonshell
charts
entity-framework-extensions
keypaths
interaction-plot