aplparse

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aplparse: An APL Parser in Standard ML

This software implements an APL parser in Standard ML.

Example

The APL program

diff ← {1↓⍵−¯1⌽⍵}
signal ← {¯50⌈50⌊50×(diff 0,⍵)÷0.01+⍵}

compiles into the following abstract syntax tree (pretty printed):

[Assign(diff,Lam(App2(Drop,1,App2(Sub,Omega,App2(Rot,-1,Omega))))),
 Assign(signal,Lam(App2(Max,-50,
                     App2(Min,50,
                       App2(Times,50,
                         App2(Div,
                           App1(diff,App2(Cat,0,Omega)),
                           App2(Add,0.01,Omega)
                         )
                       )
                     )
                   )
                  )
       )
]

Try it!

The parser compiles with either MLton or MLKit.

For compilation and use, Smackage is assumed. Add the following entry to your ~/.smackage/sources.local file:

aplparse git git://github.com/melsman/aplparse.git

Now write

$ smackage refresh
$ smackage get aplparse

The implementation builds on the unicode library available at https://github.com/melsman/unicode, but Smackage will arrange for this library to be fetched and installed automatically.

Then simply write smackage make aplparse tests in your shell.

To use the MLKit as a compiler, write instead:

$ smackage make aplparse clean
$ MLCOMP=mlkit smackage make aplparse tests

Limitations

Todo: improved error handling. Although position information is now maintained in the parser, not all parser errors are reported with relevant position information.

License

This software is published under the MIT License.