Purpose: Typically tools that map non-RDF data into RDF format rely on the technology native to the source of the data when data transformation is required. Depending on the data format, data manipulation can be performed using underlying technology, such as RDBMS for relational databases or XPath for XML. For CSV/Tabular data there is no such underlying technology, and instead it requires either a transformation of source data into another format or pre/post-processing techniques. In this paper we evaluate the state of the art in CSV uplift tools. Based on this evaluation, a method that incorporates data transformations into uplift mapping languages by means of functions is proposed and evaluated. Design/methodology/approach: In order to evaluate the state of the art in CSV uplift tools we present a comparison framework and have applied it to such tools. A key feature evaluated in the comparison framework is data transformation functions. We argue that existing approaches for transformation functions are complex-in that a number of steps and tools are required. Our proposed method, FunUL, in contrast, defines functions independent of the source data being mapped into RDF, as resources within the mapping itself. Findings: The approach was evaluated using two typical real world use cases. We have compared how well our approach and others (that include transformation functions as part of the uplift mapping) could implement an uplift mapping from CSV/Tabular into RDF. This comparison indicates that our approach performs well for these use cases. Originality/value: This paper presents a comparison framework and applies it to the state of the art in CSV uplift tools. Furthermore, we describe FunUL, which unlike other related work, defines functions as resources within the uplift mapping itself, integrating data transformation functions and mapping definitions. This makes the generation of RDF from source data transparent and traceable. Moreover, since functions are defined as resources, these can be reused multiple times within mappings.