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My company is designing a new domain specific scripting language; I have to implement a parser that translates our brand new programming language into a common scripting language so as to be able to enact it.
The usual way I do this is by means of Bison and Flex tools that generate the C/C++ code of the translator.
I found other tools, for most of the mainstream programming languages, but none for Lisp.
Hasn't Lisp ever been used for that? What is the usual way to write a parser with Lisp?
Note: to me, any Lisp implementation / dialect that could help is ok, I do not have any preference.
747
The Lispy parser is implemented with the function parse. Execution:The internal representation is then processed according to the semantic rulesof the language, thereby carrying out the computation. Lispy's execution function is called eval(note this shadows Python's built-in function of the same name).
Despite whether to implement a handwritten parser or to use a generated-parser, there is one thing that is always going to be needed: a well-defined grammar (a formal grammar) for the language we are going to implement. A grammar defines the lexical and syntactical structure of a program of that language.
In a language translator called a compilerthere is often a series of internal representations, starting with an abstract syntax tree, and progressing to a sequence of instructions that can be directly executed by the computer. The Lispy parser is implemented with the function parse.
Before we get into the details of how to write a parser, let's see what parsing actually means. Parsing essentially means converting a source-code into a tree-like object representation — which is called the ‘parse tree’ (also sometimes called the ‘syntax tree’). Often, an abstract syntax tree (AST) is confused with a parse/syntax tree.
Well, "the usual" way to do this in Common Lisp is … to do it in Lisp.
A lot of domain-specific languages (and Lisp is pretty much notoriously specialized for this purpose!) are simply written as extensions to Lisp itself, using the macro facility. The upside is, it's trivial to write a DSL. The downside is, they often tend to "look like" lisp.
Some examples of DSL's within the Common Lisp standard include the LOOP macro's own sub-language and the sub-language of the FORMAT specifiers.
Since Lisp's s-expression notation is nominally a written form of an Abstract Syntax Tree, it's one way to avoid having much of your own lexer or parser; you can just use READ.
That all being said, you can use some common packages that might be found in GRAYLEX or CL-LEXER or so forth; looking at the parsers for some other language with a similar syntax to yours might help. In Quicklisp, I see:
CL-USER> (ql:system-apropos "parse")
#<SYSTEM cl-arff-parser / cl-arff-parser-20130421-git / quicklisp 2013-08-13>
#<SYSTEM cl-date-time-parser / cl-date-time-parser-20130813-git / quicklisp 2013-08-13>
#<SYSTEM cl-html-parse / cl-html-parse-20130813-git / quicklisp 2013-08-13>
#<SYSTEM cl-html5-parser / cl-html5-parser-20130615-git / quicklisp 2013-08-13>
#<SYSTEM cl-html5-parser-tests / cl-html5-parser-20130615-git / quicklisp 2013-08-13>
#<SYSTEM cl-pdf-parser / cl-pdf-20130420-git / quicklisp 2013-08-13>
#<SYSTEM cli-parser / cl-cli-parser-20120305-cvs / quicklisp 2013-08-13>
#<SYSTEM clpython.parser / clpython-20130615-git / quicklisp 2013-08-13>
#<SYSTEM com.gigamonkeys.parser / monkeylib-parser-20120208-git / quicklisp 2013-08-13>
#<SYSTEM com.informatimago.common-lisp.html-parser / com.informatimago-20130813-git / quicklisp 2013-08-13>
#<SYSTEM com.informatimago.common-lisp.parser / com.informatimago-20130813-git / quicklisp 2013-08-13>
#<SYSTEM csv-parser / csv-parser-20111001-git / quicklisp 2013-08-13>
#<SYSTEM fucc-parser / fucc_0.2.1 / quicklisp 2013-08-13>
#<SYSTEM http-parse / http-parse-20130615-git / quicklisp 2013-08-13>
#<SYSTEM http-parse-test / http-parse-20130615-git / quicklisp 2013-08-13>
#<SYSTEM js-parser / js-parser-20120909-git / quicklisp 2013-08-13>
#<SYSTEM parse-declarations-1.0 / parse-declarations-20101006-darcs / quicklisp 2013-08-13>
#<SYSTEM parse-float / parse-float-20121125-git / quicklisp 2013-08-13>
#<SYSTEM parse-float-tests / parse-float-20121125-git / quicklisp 2013-08-13>
#<SYSTEM parse-js / parse-js-20120305-git / quicklisp 2013-08-13>
#<SYSTEM parse-number / parse-number-1.3 / quicklisp 2013-08-13>
#<SYSTEM parse-number-range / parse-number-range-1.0 / quicklisp 2013-08-13>
#<SYSTEM parse-number-tests / parse-number-1.3 / quicklisp 2013-08-13>
#<SYSTEM parse-rgb / cl-tcod-20130615-hg / quicklisp 2013-08-13>
#<SYSTEM parseltongue / parseltongue-20130312-git / quicklisp 2013-08-13>
#<SYSTEM parser-combinators / cl-parser-combinators-20121125-git / quicklisp 2013-08-13>
#<SYSTEM parser-combinators-cl-ppcre / cl-parser-combinators-20121125-git / quicklisp 2013-08-13>
#<SYSTEM parser-combinators-tests / cl-parser-combinators-20121125-git / quicklisp 2013-08-13>
#<SYSTEM py-configparser / py-configparser-20101006-svn / quicklisp 2013-08-13>
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