Wisp: Small-but-featureful embeddable Lisp interpreter written in Haskell

Re:Wisp: Small-but-featureful embeddable Lisp interpreter wr... by pygy_ on Sunday November 03, 2013 @05:05PM (#6665336)

It could be trivially implemented in Lua as a pre-processor. Lua has lambdas, higher level functions, lexical scope and tail call elimination.

The main problem is that it doesn't have a ternary operator, making conditional expression problematic to represent (you have to wrap an if statement in a lambda called on the fly).

For something more fully featured, see [0], it is written in MoonScript (which itself compiles to Lua), and the parser depends on LPeg, but writing a S-expression parser is rather easy.

Edit: There's also lcl [1], which is implemented in C. Written by lhf, one of the Lua authors. From the test files, it looks very basic.

[0] https://github.com/leafo/moonlisp/tree/master/lisp

[1] http://www.drdobbs.com/open-source/lua-an-extensible-embedde...

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Re:Wisp: Small-but-featureful embeddable Lisp interpreter wr... by _mpu on Sunday November 03, 2013 @06:15PM (#6665593)

Wrapping an if in a lambda is unlikely to work as expected.

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Re:Wisp: Small-but-featureful embeddable Lisp interpreter wr... by pygy_ on Sunday November 03, 2013 @06:35PM (#6665647)

    ((if foo + -) 4 6)

Can be compiled to

    (function()
        if foo then return plus
        else return minus
        end
    end)()(4, 6)

It is far too verbose to be used in manually crafted Lua, but acceptable if you treat it as a compiler target (with the caveat that the lambda creation will prevent LuaJIT from JITting that piece of code).

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Re:Wisp: Small-but-featureful embeddable Lisp interpreter wr... by meric on Monday November 04, 2013 @05:47AM (#6667894)

Plug https://github.com/meric/l2l

"A object-oriented, unicode-enabled lisp that compiles to and runs as fast as Lua. Equipped with macros and compile-time compiler manipulation. Comes with all built-in Lua functions."

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Re:Wisp: Small-but-featureful embeddable Lisp interpreter wr... by pygy_ on Monday November 04, 2013 @05:54PM (#6671786)

Nice one! I started coding one after writing the above comment.

I have a question regarding your implementation: why do you use `goto`s rather than `elseif` to compile `(cond)` blocks? For nested blocks?

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Re:Wisp: Small-but-featureful embeddable Lisp interpreter wr... by meric on Sunday November 10, 2013 @01:21AM (#6705526)

Oh I think it it was for the return value of cond.

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