On Wed, Oct 25, 2000 at 09:03:43AM -0700, Doug Ransom wrote:
I would like to be able to inspect the type of things easily by hovering my mouse over an expression. As a beginner, I find it hard sometimes to get types correct in Haskell since often variables are not declared as a specific type.
Since you are typically dealing with incomplete programs in an editor this is really tough. The PSG system was able to generate such editors and I once saw it for the purely functional language Sample in action: you could mark any term with the mouse cursor and ask for its type. -- Christian @Article{Bahlke:1986:PSG, author = "Rolf Bahlke and Gregor Snelting", title = "The {PSG} System: From Formal Language Definitions to Interactive Programming Environments", journal = "ACM Transactions on Programming Languages and Systems", volume = "8", number = "4", pages = "547--576", month = oct, year = "1986", coden = "ATPSDT", ISSN = "0164-0925", bibdate = "Sat Jan 06 09:41:04 1996", url = "http://www.acm.org/pubs/toc/Abstracts/0164-0925/20890.html", abstract = "The PSG programming system generator developed at the Technical University of Darmstadt produces interactive, language-specific programming environments from formal language definitions. All language-dependent parts of the environment are generated from an entirely nonprocedural specification of the language's syntax, context conditions, and dynamic semantics. The generated environment consists of a language-based editor, supporting systematic program development by named program fragments, an interpreter, and a fragment library system. The major component of the environment is a full-screen editor, which allows both structure and text editing. In structure mode the editor guarantees prevention of both syntactic and semantic errors, whereas in textual semantic analysis which is based on unification. The algorithm will immediately detect semantic errors even in incomplete program fragments. The dynamic semantics of the language are defined in denotational style using a functional language based on the lambda calculus. Program fragments are compiled to terms of the functional language which are executed by an interpreter. The PSG generator has been used to produce environments for Pascal, ALGOL 60, MODULA-2, and the formal language definition language itself.", acknowledgement = ack-pb # " and " # ack-nhfb, keywords = "algorithms; design; documentation; languages; theory; theory and verification and Hybrid editor and unification-based incremental semantic analysis; verification", owner = "manning", review = "ACM CR 8711-0926", subject = "{\bf D.3.4}: Software, PROGRAMMING LANGUAGES, Processors, Compilers. {\bf D.2.3}: Software, SOFTWARE ENGINEERING, Coding, Program editors. {\bf D.2.6}: Software, SOFTWARE ENGINEERING, Programming Environments. {\bf D.3.1}: Software, PROGRAMMING LANGUAGES, Formal Definitions and Theory, Semantics. {\bf D.3.1}: Software, PROGRAMMING LANGUAGES, Formal Definitions and Theory, Syntax. {\bf D.2.3}: Software, SOFTWARE ENGINEERING, Coding, Pretty printers. {\bf F.3.2}: Theory of Computation, LOGICS AND MEANINGS OF PROGRAMS, Semantics of Programming Languages. {\bf F.4.2}: Theory of Computation, MATHEMATICAL LOGIC AND FORMAL LANGUAGES, Grammars and Other Rewriting Systems, Grammar types. {\bf F.4.2}: Theory of Computation, MATHEMATICAL LOGIC AND FORMAL LANGUAGES, Grammars and Other Rewriting Systems, Parsing. {\bf I.2.3}: Computing Methodologies, ARTIFICIAL INTELLIGENCE, Deduction and Theorem Proving, Deduction.", } -- Christian Lindig Harvard University - DEAS lindig@eecs.harvard.edu 33 Oxford St, MD 242, Cambridge MA 02138 phone: +1 (617) 496-7157 http://www.eecs.harvard.edu/~lindig/