The top-level call
{{ partial "a.html" (dict "ctx" . "partialsToRender" (slice "componentA.html" "componentB.html" )) }}
layouts/partials/a.html
{{ range .partialsToRender }}
{{ if templates.Exists (printf "partials/%s" .) }}
{{ partial . $.ctx }}
{{ else }}
{{ errorf "Partial %q not found" . }}
{{ end }}
{{ end }}