This paper gives a first experience report about programming with a

 TODO

 TP-based programming language.

 \medskip A brief re-introduction of the novel kind of programming

 language by example of the {\sisac}-prototype makes the paper

 self-contained. The main section describes all the main concepts

 involved in TP-based programming and all the sub-tasks concerning

 respective implementation: mechanisation of mathematics and domain

 modelling, implementation of term rewriting systems for the

 rewriting-engine, formal (implicit) specification of the problem to be

 (explicitly) described by the program, implement the many components

 required for Lucas-Interpretation and finally implementation of the

 program itself.

 The many concepts and sub-tasks involved in programming require a

 comprehensive workflow; first experiences with the workflow as

 supported by the present prototype are described as well: Isabelle +

 Isar + jEdit provide appropriate components for establishing an

 efficient development environment integrating computation and

 deduction. However, the present state of the prototype is far off a

 state appropriate for wide-spread use: the prototype of the program

 language lacks expressiveness and elegance, the prototype of the

 development environment is hardly usable: error messages still address

 the developer of the prototype's interpreter rather than the

 application programmer, implementation of the many settings for the

 Lucas-Interpreter is cumbersome.

 From these experiences a successful proof of concept can be concluded:

 programming arbitrary problems from engineering sciences is possible,

 in principle even in the prototype. Furthermore the experiences allow

 to conclude detailed requirements for further development:

 \begin{itemize}

 \item Clarify underlying logics such that programming is smoothly

 integrated with verification of the program; the post-condition should

 be proved more or less automatically, otherwise working engineers

 would not encounter such programming.

 \item Combine the prototype's programming language with Isabelle's

 powerful function package and probably with more of SML's

 pattern-matching features; include parallel execution on multi-core

 machines into the language desing.

 \item Extend the prototype's Lucas-Interpreter such that it also

 handles functions defined by use of Isabelle's functions package; and

 generalize Isabelle's code generator such that efficient code for the

 whole of the defined programming language can be generated (for

 multi-core machines).

 \item Develop an efficient development environment with

 integration of programming and proving, with management not only of

 Isabelle theories, but also of large collections of specifications and

 of programs.

 \end{itemize} 

 Provided successful accomplishment, these points provide distinguished

 components for virtual workbenches appealing to practictioner of

 engineering in the near future.

 \medskip And all programming with a TP-based language will

 subsequently create interactive tutoring as a side-effect:

 Lucas-Interpretation not only provides an interactive programming

 environment, Lucas-Interpretation also can provide TP-based services

 for a flexible dialog component with adaptive user guidance for

 independent and inquiry-based learning.