evalexpr | A powerful expression evaluation crate for Rust | Interpreter library

I assume that we are dealing the case of Const the following way:

You write

Assuming you've created a project using cabal or stack, then your Expr module should be in src/Expr.hs and your Main module should be in src/Main.hs or app/Main.hs. The code you have looks at first glance like it should compile and run fine.

You can then either run a REPL instance (cabal repl or stack repl) in your project directory and call the main function from there or you can run it as an executable (cabal run or stack run) and pass in your arguments from the command-line.

If you haven't created a project using either of the tools I mentioned above, then this documentation should prove useful:

• Cabal documentation
• Stack documentation

Edit:

I had neglected to look at the code in detail before/try to compile & run it.

Your main function has some issues with the pattern match line of:

To add evaluation add eval() methods to each of your classes. Each eval() method will perform the respective operation on your lists of bools:

Your issue is that the result type of f is different in different branches, which is not allowed. In the first two it is (e.g.) Int -> Int, the type of (+) 3 (which is the same as \x -> 3 + x. The type of the third and fourth lines is just Int. These types are not the same.

Here is a simple solution.

When I run your code this is the exception I get:

This a scoping issue in anova.cca(..., by="axis") which should find items from several different environments when it is updating the formula (I won't go into technical details). You really cannot embed the function to analyse the significances of axes. This is a known issue. We have solved that in the development version of vegan. The re-designed function in https://github.com/vegandevs/vegan seemed to work with this example. All ordination and significance functions are radically changed there, and they are not yet completely finished. We plan to release them in vegan 2.5-0 in the last quarter of 2017, but they are not finished yet.

The problem is that anova.cca(..., by = "axis") must find items that it builds within the function, and in addition it can find items that were available when the original model was built, but it cannot find items that you generate in functions that embed the function. You must circumvent this by making your embedding function to write its objects somewhere that these can be found. The easiest (but dirty) solution is to write them into parent environment with <<-. The following version of your function adds this <<- and seems to work in vegan 2.4-3