(module what mzscheme
  (require "../private/util.ss"
           "../../private/manuals.ss"
           "../private/headelts.ss"
           (lib "servlet.ss" "web-server"))
  (provide interface-version timeout start)
  (define interface-version 'v1)
  (define timeout +inf.0)

  (define (start initial-request)

    (define stupid-internal-define-syntax
      (report-errors-to-browser send/finish))

    (define (standout-text s)
      (with-color "forestgreen" `(B ,s)))

    `(HTML
      (HEAD ,hd-css ,@hd-links (TITLE "Scheme Languages"))
      (BODY
       (H1 "Scheme Languages")
       (A ([NAME "scheme"] [VALUE "Language Family"]))
       (A ([NAME "r5rs"] [VALUE "r5rs"]))
       (A ([NAME "language levels"] [VALUE "language levels"]))
       "From the introduction of " ,(main-manual-page "r5rs") " (R5RS):"
       (P)
       (DL (DD "Scheme is a statically scoped and properly "
               "tail-recursive dialect of the Lisp programming "
               "language [...] designed to have an exceptionally "
               "clear and simple semantics and few different ways "
               "to form expressions. A wide variety of programming "
               "paradigms, including imperative, functional, and "
               "message passing styles, find convenient expression "
               "in Scheme."))
       (P)
       "DrScheme supports many dialects of Scheme. "
       "The following dialects are specifically designed for "
       "teaching computer science.  In DrScheme's "
       (A ([HREF "/servlets/scheme/what.ss#lang-sel"])
          "language selection menu")
       ", they are found under the heading " (B "How to Design Programs") "."
       (UL
        (LI
         (A ([NAME "beg"] [VALUE "Beginning Student language"]))
         ,(standout-text "Beginning Student")
         " is a pedagogical version of Scheme "
         "that is tailored for beginning computer "
         "science students.")
        (LI
         (A ([NAME "begla"] [VALUE "Beginning Student with List Abbreviations language"]))
         ,(standout-text "Beginning Student with List Abbreviations")
         " extends Beginning Student with convenient "
         "(but potentially confusing) ways to write lists, "
         "including quasiquote.")
        (LI
         (A ([NAME "int"] [VALUE "Intermediate Student language"]))
         ,(standout-text "Intermediate Student")
         " adds local bindings and higher-order functions.")
        (LI
         (A ([NAME "intlam"] [VALUE "Intermediate Student with Lambda language"]))
         ,(standout-text "Intermediate Student with Lambda")
         " adds anonymous functions.")
        (LI
         (A ([NAME "adv"] [VALUE "Advanced Student language"]))
         ,(standout-text "Advanced Student")
         " adds mutable state."))
       "The "
       ,(standout-text "Essentials of Programming Languages")
       " language is designed for use with the MIT Press "
       "textbook with that name."
       (P)
       "Other dialects are designed for practicing programmers. "
       "The " (A ([NAME "r5rs2"] [VALUE "R5RS Scheme language"]))
       ,(standout-text "R5RS")
       " language is a standard dialect of Scheme that is "
       "defined by the "
       ,(main-manual-page "r5rs") ". "
       (A ([NAME "full"] [VALUE "PLT Scheme language"]))
       "In DrScheme's "
       (A ([HREF "/servlets/scheme/what.ss#lang-sel"])
          "language selection menu")
       ", the following languages "
       "are found under the heading " (B "PLT") ":"
       (UL
        (LI
         ,(standout-text "Textual (MzScheme)")
         " is a superset of R5RS Scheme. "
         "In addition to the the base Scheme language, "
         "PLT Scheme provides exceptions, threads, "
         "objects, modules, components, regular expressions, "
         "TCP support, filesystem utilities, and process "
         "control operations. This language is defined in "
         ,(main-manual-page "mzscheme")
         ". ")
        (LI
         ,(standout-text "Graphical (MrEd)")
         " includes the " (standout-text "Textual (MzScheme)") " language "
         "and adds a graphical toolbox, "
         "described in "
         ,(main-manual-page "mred") ".")
        (LI ,(standout-text "Pretty Big")
            " is a superset of the "
            (standout-text "Graphical (MrEd)")
            " language, and adds forms from the "
            (standout-text "Pretty Big")
            " language."
            " For those forms that are in both languages,"
            " Pretty Big behaves like Graphical (MrEd)."))
       "The "
       (A ([NAME "module"] [VALUE "module"]))
       ,(standout-text "module")
       " language supports development using PLT Scheme's "
       ,(manual-entry "mzscheme" "modules" `(CODE "module"))
       " form, where the module's language is explicitly "
       "declared in the code."
       (P)
       "See "
       ,(manual-entry "drscheme" "language levels" "the DrScheme manual")
       " for further details on the languages, "
       "especially the teaching languages."
       (P)
       "DrScheme's set of languages can be extended, "
       "so the above list mentions only the languages installed "
       "by default. "
       "Documentation for all languages is available "
       "through the "
       (A ([HREF "/servlets/manuals.ss"]) "manuals page") "."
       (P)
       (A ([NAME "lang-sel"] [VALUE "language, setting"]))
       "DrScheme's default language is Beginning Student. "
       "To change the language, select the "
       (B  "Choose Language...")
       " item in the "
       (B "Language") " menu."))))