Various code written at various times in Ur/Web. Not all of it is useful in its current state.
This is a toy relational algebra query evaluator, embedded in
Ur/Web. Please find the test case in tests/rel.ur, or view the
result.
Features:
- first-class relation variables (and they are typed precisely, meaning the underlying row type is tracked statically)
- relvar operators that allow manipulation of relvars:
empty(for an empty relvar) *insert(to insert a row into a relvar)
- query operators (these will never modify their inputs):
project(to project out a column from a relvar)join(to perform a natural equi-join of two relations)restrict(to apply a predicate to a relvar)union(set union of two relvars)difference(set difference of two relvars)times(cross-join of two relvars)
To run: please build it via urweb rel, run ./rel.exe and navigate
to http://localhost:8080/main.
This is serialization/deserialization in one go based on Andrew Kennedy's paper Pickler Combinators.
I used something similar in an F# prototype at work, but it was way too tedious to handle n-ary tuples. Metaprogramming based on row types to the rescue!
This is just a demo to show that drag-n-drop is possible to write in
pure Ur/Web. To run, please build it via urweb dragdrop, run
./dragdrop.exe, and navigate to http://localhost:8080/main.
I also left some quirky notes for a hypothetical future extension to Ur/Web to handle HTML5 drag and drop API.
These are taken verbatim from another project. The modules are unlikely to build, at this point.