Command: validate

/literal -> boolean

The function validate checks whether the examples in the documentation
of the function specified by the literal argument work as documented.
Every example in the example section is expected to result in a boolean
value. validate only returns true if the result of all examples is true.
In order to make the documentation of examples more readable validate
supports a special (infix) syntax for the examples:
a1 ... an --> b1
is translated to
a b eq
assuming that the sequence ai collapses to a and the sequence bj to b.
Thus --> has delayed execution time and is only processed after all
expressions in the example section have been executed once. The -->
expressions can be freely mixed with regular SLI code boolean
expressions like
a b eq
The documentation of function Part contains several examples.

Before a function can be validated it needs to be registered with the
help system. This is required because in SLI several functions can be
defined in the same source file. Thus only after processing the source
file SLI is aware of the functions implemented by this file. The help
system of SLI stores the path to the implementing file with the
documentation of each function. Therefore SLI can lookup the source
code for each function without searching.

The typical workflow in test driven programming in SLI is as follows:
1. create a new file myfunctions.sli
2. write documentation including examples for one or
more functions e.g. /myfunc1
3. call (myfunctions.sli) makehelp
4. implement /myfunc1
5. call /myfunc1 validate
6. continue with 4 (not 3) until validate is successful

The algorithm of function validate is as follows:
1. find the help file (.hlp) for the specified function. If not
found ask for running makehelp for first time registration of
the function
2. obtain the source file implementing the function
from the help file
3. update the help file of the function
4. construct target path for test files
5. write some header
6. copy the invariants
7. write some footer
8. run the test file


The function is experimental. It constitutes a first attempt to
provide support for test driven programming in NEST. A variant of
this function could easily print a detailed report of the test results
and the intermediate generation of a test script is not necessary.
In the present implementation validate updates the plain text help file
(.hlp) but not the hypertext help (.html).

/Part validate --> true
% /validate validate --> true % infinite recursion