scribbled macro-debugger docs
svn: r8542
This commit is contained in:
Ryan Culpepper
parent
75b8275231
commit
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@ -1,312 +0,0 @@
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_Macro Debugger_
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================
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Keywords: _syntax_, _syntax-browser_, _hygiene_,
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_referential transparency_, _lexical context_,
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_macro_, _expansion_, _macro-debugger_, _macro-stepper_
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OUTLINE
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=======
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* Introduction
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* APIs
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- expand.ss
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- syntax-browser.ss
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* Using the macro stepper
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* Using the syntax browser
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* Enabling the macro stepper in other languages
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* Notes for DrScheme language implementors
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Introduction
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============
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The macro-debugger collection contains two tools: a stepper for macro
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expansion and a standalone syntax browser. The macro stepper shows the
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programmer the expansion of a program as a sequence of rewriting
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steps, using the syntax browser to display the individual terms. The
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syntax browser uses colors and a properties panel to show the term's
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syntax properties, such as lexical binding information and source
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location.
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_stepper.ss_
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============
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> (require (lib "stepper.ss" "macro-debugger"))
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This module provides a single procedure:
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> (expand/step syntax-or-sexpr)
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Expands the syntax (or S-expression) and opens a macro stepper frame
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for stepping through the expansion. Returns an object of
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macro-stepper<%> with the following methods:
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> (send a-macro-stepper at-start?) -> boolean
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> (send a-macro-stepper at-end?) -> boolean
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> (send a-macro-stepper navigate-to-start) -> void
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> (send a-macro-stepper navigate-to-end) -> void
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> (send a-macro-stepper navigate-previous) -> void
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> (send a-macro-stepper navigate-next) -> void
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> (send a-macro-stepper navigate-forward/count n) -> void
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> (send a-macro-stepper navigate-forward/pred pred) -> void
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pred : syntax -> boolean
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Navigate forward to an expansion with redex (focus) matching pred.
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> (send a-macro-stepper at-top?) -> boolean
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> (send a-macro-stepper at-bottom?) -> boolean
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> (send a-macro-stepper navigate-up) -> void
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> (send a-macro-stepper navigate-down) -> void
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> (send a-macro-stepper navigate-down/pred pred) -> void
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pred : syntax -> boolean
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Navigate down to an expansion with initial syntax satisfying pred.
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_expand.ss_
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===========
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> (require (lib "expand.ss" "macro-debugger"))
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This module provides the following procedures:
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> (expand-only syntax list-of-identifiers)
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Expands the given syntax, but only shows the expansion of macros in
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the given identifier list.
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Warning: because of limitations in syntax, expansion, and hiding, the
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resulting syntax may not evaluate to the same thing as the original
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syntax.
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> (expand/hide syntax list-of-identifier)
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Expands the given syntax, but hides the expansion of macros in the
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given identifier list (conceptually, the complement of expand-only).
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Warning: because of limitations in syntax, expansion, and hiding, the
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resulting syntax may not evaluate to the same thing as the original
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syntax.
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_stepper-text.ss_
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=================
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> (require (lib "stepper-text.ss" "macro-debugger"))
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This module provides two procedures for stepping through macro
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expansion in text-only environments.
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> (expand/step-text syntax [identifier-predicate])
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Expands the syntax and prints the macro expansion steps. If the
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identifier predicate is given, it determines which macros are shown
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(if absent, no macros are hidden). A list of identifiers is also
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accepted.
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> (stepper-text syntax [identifier-predicate])
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Returns a procedure P that:
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- when called with no arguments (or on the symbol 'next),
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prints out individual steps until macro expansion finishes
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- when called on the symbol 'all,
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prints out all of the remaining steps
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_syntax-browser.ss_
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===================
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> (require (lib "syntax-browser.ss" "macro-debugger"))
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This module provides the following procedures:
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> (browse-syntax syntax) -> void
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Creates a frame with the given syntax object shown. More information
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on using the GUI is available below.
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> (browse-syntaxes list-of-syntax) -> void
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Like browse-syntax, but shows multiple syntax objects in the same
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frame. The coloring partitions are shared between the two,
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showing the relationships between subterms in different syntax
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objects.
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> (syntax-snip syntax) -> (is-a?/c snip%)
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Like 'browse-syntax', but creates a snip that can be displayed in an
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editor. In particular, evaluating
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(syntax-snip <stx>)
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in DrScheme's interactions window will insert a syntax browser into
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the interactions window.
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Using the Macro Stepper
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=======================
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Navigation
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----------
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The stepper presents expansion as a linear sequence of rewriting
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process, and it gives the user controls to step forward or backwards
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as well as to jump to the beginning or end of the expansion process.
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If the macro stepper is showing multiple expansions, then it also
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provides "Previous term" and "Next term" buttons to go up and down in
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the list of expansions. Horizontal lines delimit the current expansion
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from the others.
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Macro hiding
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------------
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Macro hiding lets one see how expansion would look if certain macros
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were actually primitive syntactic forms. The macro stepper skips over
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the expansion of the macros you designate as opaque, but it still
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shows the expansion of their subterms.
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The bottom panel of the macro stepper controls the macro hiding
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policy. The user changes the policy by selecting an identifier in the
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syntax browser pane and then clicking one of "Hide module", "Hide
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macro", or "Show macro". The new rule appears in the policy display,
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and the user may later remove it using the "Delete" button.
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The stepper also offers coarser-grained options that can hide
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collections of modules at once. These options have lower precedence
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than the rules above.
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Macro hiding, even with no macros marked opaque, also hides certain
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other kinds of steps: internal defines are not rewritten to letrecs,
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begin forms are not spliced into module or block bodies, etc.
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Using the Syntax Browser
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========================
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Selection (bold)
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----------------
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The user can click on any part of a subterm to *select* it. To select
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a parenthesized subterm, click on either of the parentheses. The
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selected syntax is bolded. Since one syntax object may occur
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inside of multiple other syntax objects, clicking on one occurrence
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will cause all occurrences to be bolded.
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The syntax browser displays information about the selected syntax
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object in the properties panel on the right, when that panel is
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shown. The selected syntax also determines the highlighting done by
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the secondary partitioning (see below).
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Primary partition (foreground color)
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------------------------------------
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The *primary partitioning* always assigns two syntax subterms the same
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color if they have the same marks. In the absence of unhygienic
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macros, this means that subterms with the same foreground color were
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either present in the original pre-expansion syntax or generated by
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the same macro transformation step.
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Syntax colored in black always corresponds to unmarked syntax. Such
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syntax may be original, or it may be produced by the expansion of a
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nonhygienic macro.
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Secondary partitioning (highlight)
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----------------------------------
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The user may select a *secondary partitioning* from a drop-down box
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(or in the macro stepper, through the Syntax menu). This partitioning
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applies only to identifiers. When the user selects an identifier, all
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terms in the same equivalence class as the selected term are
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highlighted in yellow.
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The available secondary partitionings are:
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* bound-identifier=?
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* module-identifier=?
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* module-or-top-identifier=?
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See the documentation for these predicates in the MzScheme manual.
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* symbolic-identifer=?
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Two identifiers are symbolic-identifier=? if discarding all lexical
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context information yields the same symbol.
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* same marks
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Two identifiers have the same marks if (barring nonhygienic macros)
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they were produced by the same macro transformation step.
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* same source module
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The bindings of the two identifiers come from definitions in the
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same module.
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* same nominal module
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The bindings of the two identifiers were imported into the current
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context by requiring the same module.
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Properties
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----------
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When the properties pane is shown, it displays properties of the
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selected syntax object. The properties pane has three tabbed pages:
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- Binding
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If the selection is an identifier, shows the binding information
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associated with the syntax object.
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*Note: See the warning in the section below.
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For more information, look up 'identifier-binding',
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'identifier-transformer-binding', and
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'identifier-template-binding' in the Help Desk.
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- Source
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Displays source location information about the syntax object.
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- Properties
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Displays properties (see 'syntax-property') of the selection
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when it has properties it knows the keys for.
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Warnings about interpreting syntax
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----------------------------------
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The binding information of a *syntax object* may not be the same as
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the binding structure of the *program* it represents. The binding
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structure of a *program* is only determined after macro expansion is
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complete.
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Example: (browse-syntax #'(lambda (foo) foo))
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The syntax browser will report that the inner 'foo' is unbound, even
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though in the *program* that this syntax represents, the inner 'foo'
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is bound to the outer 'foo'.
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Notes and Limitations
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---------------------
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The syntax browser does not have a way of extending the set of
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available secondary partitions.
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The syntax browser does not have a way of extending the set of known
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properties.
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The syntax browser does not preserve the distinction between
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parentheses and square brackets.
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Notes for DrScheme language implementors
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========================================
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The macro stepper works "out of the box" only with certain languages
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out of all the languages available from the DrScheme languages
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menu. For example, the macro stepper is disabled for the teaching
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languages.
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An implementor of a new DrScheme language can designate their language
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"macro-steppable" by overriding the 'enable-macro-stepper?' method of
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their implementation of 'drscheme:language:language<%>'. The default
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implementation in the mixin provided by
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'drscheme:language:get-default-mixin' returns false; override this
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method to return true if the macro stepper button should be shown for
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this language.
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Note: There is currently no way to customize the behavior of the macro
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stepper for different languages. When enabled, the macro stepper sees
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exactly those terms that pass through the 'current-eval' handler.
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@ -3,3 +3,4 @@
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(define name "Macro Debugger")
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(define tools '(["tool.ss"]))
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(define tool-names '("Macro Stepper"))
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(define scribblings '(("macro-debugger.scrbl")))
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307
collects/macro-debugger/macro-debugger.scrbl
Normal file
307
collects/macro-debugger/macro-debugger.scrbl
Normal file
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@ -0,0 +1,307 @@
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#lang scribble/doc
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@(require scribble/manual
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scribble/struct
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scribble/eval
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(for-label scheme/base
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macro-debugger/expand
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macro-debugger/stepper
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macro-debugger/stepper-text
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macro-debugger/syntax-browser
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(rename-in scheme (free-identifier=? module-identifier=?))))
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@(define the-eval
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(let ([the-eval (make-base-eval)])
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(the-eval '(require macro-debugger/expand
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macro-debugger/stepper-text))
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the-eval))
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@title{Macro debugger}
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The macro-debugger collection contains two tools: a stepper for macro
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expansion and a standalone syntax browser. The macro stepper shows the
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programmer the expansion of a program as a sequence of rewriting
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steps, using the syntax browser to display the individual terms. The
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syntax browser uses colors and a properties panel to show the term's
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syntax properties, such as lexical binding information and source
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location.
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@section{Macro stepper}
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@defmodule[macro-debugger/stepper]
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@defproc[(expand/step [stx any/c])
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(is-a/c macro-stepper<%>)]{
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Expands the syntax (or S-expression) and opens a macro stepper frame
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for stepping through the expansion.
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}
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@definterface[macro-stepper<%> ()]{
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@defmethod[(at-start?) boolean?]
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@defmethod[(at-end?) boolean?]
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@defmethod[(navigate-to-start) void?]
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@defmethod[(navigate-to-end) void?]
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@defmethod[(navigate-previous) void?]
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@defmethod[(navigate-next) void?]
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@defmethod[(at-top?) boolean?]
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@defmethod[(at-bottom?) boolean?]
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@defmethod[(navigate-up) void?]
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@defmethod[(navigate-down) void?]
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}
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@section{Macro expansion tools}
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@defmodule[macro-debugger/expand]
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@defproc[(expand-only [stx any/c] [transparent-macros (listof identifier?)])
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syntax?]{
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Expands the given syntax @scheme[stx], but only shows the expansion
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of macros whose names occur in @scheme[transparent-macros].
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@(examples #:eval the-eval
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(syntax->datum
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(expand-only #'(let ([x 1] [y 2]) (or (even? x) (even? y)))
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(list #'or))))
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Warning: because of limitations in syntax, expansion, and hiding,
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the resulting syntax may not evaluate to the same thing as the
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original syntax.
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}
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@defproc[(expand/hide [stx any/c] [hidden-macros (listof identifier?)])
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syntax?]{
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Expands the given syntax @scheme[stx], but hides the expansion of macros in the
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given identifier list (conceptually, the complement of expand-only).
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@(examples #:eval the-eval
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(syntax->datum
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(expand/hide #'(let ([x 1] [y 2]) (or (even? x) (even? y)))
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(list #'or))))
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Warning: because of limitations in syntax, expansion, and hiding,
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the resulting syntax may not evaluate to the same thing as the
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original syntax.
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}
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@section{Macro stepper text interface}
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@defmodule[macro-debugger/stepper-text]
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@defproc[(expand/step-text [stx any/c]
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[macro-policy (or/c (-> identifier? boolean?)
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(listof identifier?))
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null])
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void?]{
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|
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Expands the syntax and prints the macro expansion steps. If the
|
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identifier predicate is given, it determines which macros are shown
|
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(if absent, no macros are hidden). A list of identifiers is also
|
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accepted.
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|
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@(examples #:eval the-eval
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(expand/step-text #'(let ([x 1]) (even? x)))
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#;(expand/step-text #'(let ([x 1] [y 2]) (or (even? x) (even? y)))
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(lambda (id) (eq? (syntax-e id) 'or))))
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}
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@defproc[(stepper-text [stx any/c]
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[macro-policy (or/c (-> identifier? boolean?)
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(listof identifier?))])
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(symbol? -> void?)]{
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|
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Returns a procedure that can be called on the symbol
|
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@scheme['next] to print the next step or on the symbol
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@scheme['all] to print out all remaining steps.
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}
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@section{Syntax browser}
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@defmodule[macro-debugger/syntax-browser]
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@defproc[(browse-syntax [stx syntax?])
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void?]{
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Creates a frame with the given syntax object shown. More information
|
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on using the GUI is available below.
|
||||
}
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|
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@defproc[(browse-syntaxes [stxs (listof syntax?)])
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void?]{
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|
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Like @scheme[browse-syntax], but shows multiple syntax objects in
|
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the same frame. The coloring partitions are shared between the two,
|
||||
showing the relationships between subterms in different syntax
|
||||
objects.
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||||
}
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|
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@;{
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@defproc[(syntax-snip [stx syntax?])
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(is-a/c snip%)]{
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|
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Like @scheme[browse-syntax], but creates a snip that can be
|
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displayed in an editor.
|
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}
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}
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|
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@section{Using the macro stepper}
|
||||
|
||||
@subsection{Navigation}
|
||||
|
||||
The stepper presents expansion as a linear sequence of rewriting
|
||||
process, and it gives the user controls to step forward or backwards
|
||||
as well as to jump to the beginning or end of the expansion process.
|
||||
|
||||
If the macro stepper is showing multiple expansions, then it also
|
||||
provides "Previous term" and "Next term" buttons to go up and down in
|
||||
the list of expansions. Horizontal lines delimit the current expansion
|
||||
from the others.
|
||||
|
||||
@subsection{Macro hiding}
|
||||
|
||||
Macro hiding lets one see how expansion would look if certain macros
|
||||
were actually primitive syntactic forms. The macro stepper skips over
|
||||
the expansion of the macros you designate as opaque, but it still
|
||||
shows the expansion of their subterms.
|
||||
|
||||
The bottom panel of the macro stepper controls the macro hiding
|
||||
policy. The user changes the policy by selecting an identifier in the
|
||||
syntax browser pane and then clicking one of "Hide module", "Hide
|
||||
macro", or "Show macro". The new rule appears in the policy display,
|
||||
and the user may later remove it using the "Delete" button.
|
||||
|
||||
The stepper also offers coarser-grained options that can hide
|
||||
collections of modules at once. These options have lower precedence
|
||||
than the rules above.
|
||||
|
||||
Macro hiding, even with no macros marked opaque, also hides certain
|
||||
other kinds of steps: internal defines are not rewritten to letrecs,
|
||||
begin forms are not spliced into module or block bodies, etc.
|
||||
|
||||
@section{Using the syntax browser}
|
||||
|
||||
@subsection{Selection (bold)}
|
||||
|
||||
The user can click on any part of a subterm to select it. To select a
|
||||
parenthesized subterm, click on either of the parentheses. The
|
||||
selected syntax is bolded. Since one syntax object may occur inside of
|
||||
multiple other syntax objects, clicking on one occurrence will cause
|
||||
all occurrences to be bolded.
|
||||
|
||||
The syntax browser displays information about the selected syntax
|
||||
object in the properties panel on the right, when that panel is
|
||||
shown. The selected syntax also determines the highlighting done by
|
||||
the secondary partitioning (see below).
|
||||
|
||||
@subsection{Primary partition (foreground color)}
|
||||
|
||||
The primary partitioning always assigns two syntax subterms the same
|
||||
color if they have the same marks. In the absence of unhygienic
|
||||
macros, this means that subterms with the same foreground color were
|
||||
either present in the original pre-expansion syntax or generated by
|
||||
the same macro transformation step.
|
||||
|
||||
Syntax colored in black always corresponds to unmarked syntax. Such
|
||||
syntax may be original, or it may be produced by the expansion of a
|
||||
nonhygienic macro.
|
||||
|
||||
@subsection{Secondary partitioning (highlight)}
|
||||
|
||||
The user may select a *secondary partitioning* from a drop-down box
|
||||
(or in the macro stepper, through the Syntax menu). This partitioning
|
||||
applies only to identifiers. When the user selects an identifier, all
|
||||
terms in the same equivalence class as the selected term are
|
||||
highlighted in yellow.
|
||||
|
||||
The available secondary partitionings are:
|
||||
@itemize{
|
||||
@item{@scheme[bound-identifier=?]}
|
||||
@item{@scheme[module-identifier=?]}
|
||||
@item{@scheme[module-or-top-identifier=?]}
|
||||
@item{@bold{symbolic-identifier=?}:
|
||||
Two identifiers are symbolic-identifier=? if discarding all lexical
|
||||
context information yields the same symbol.
|
||||
}
|
||||
@item{@bold{same marks}:
|
||||
Two identifiers have the same marks if (barring nonhygienic macros)
|
||||
they were produced by the same macro transformation step.
|
||||
}
|
||||
@item{@bold{same source module}:
|
||||
The bindings of the two identifiers come from definitions in the
|
||||
same module.
|
||||
}
|
||||
@item{@bold{same nominal module}:
|
||||
The bindings of the two identifiers were imported into the current
|
||||
context by requiring the same module.
|
||||
}
|
||||
}
|
||||
|
||||
@subsection{Properties}
|
||||
|
||||
When the properties pane is shown, it displays properties of the
|
||||
selected syntax object. The properties pane has three tabbed pages:
|
||||
|
||||
- Binding
|
||||
|
||||
If the selection is an identifier, shows the binding information
|
||||
associated with the syntax object.
|
||||
|
||||
*Note: See the warning in the section below.
|
||||
|
||||
For more information, look up 'identifier-binding',
|
||||
'identifier-transformer-binding', and
|
||||
'identifier-template-binding' in the Help Desk.
|
||||
|
||||
- Source
|
||||
|
||||
Displays source location information about the syntax object.
|
||||
|
||||
- Properties
|
||||
|
||||
Displays properties (see 'syntax-property') of the selection
|
||||
when it has properties it knows the keys for.
|
||||
|
||||
@subsection{Warnings about interpreting syntax}
|
||||
|
||||
The binding information of a *syntax object* may not be the same as
|
||||
the binding structure of the *program* it represents. The binding
|
||||
structure of a *program* is only determined after macro expansion is
|
||||
complete.
|
||||
|
||||
For example, in @schemeblock[(browse-syntax #'(lambda (foo) foo))]
|
||||
the syntax browser will report that the inner 'foo' is unbound, even
|
||||
though in the *program* that this syntax represents, the inner 'foo'
|
||||
is bound to the outer 'foo'.
|
||||
|
||||
@subsection{Notes and Limitations}
|
||||
|
||||
The syntax browser does not have a way of extending the set of
|
||||
available secondary partitions.
|
||||
|
||||
The syntax browser does not have a way of extending the set of known
|
||||
properties.
|
||||
|
||||
The syntax browser does not preserve the distinction between
|
||||
parentheses and square brackets.
|
||||
|
||||
|
||||
@section{Notes for DrScheme language implementors}
|
||||
|
||||
The macro stepper works "out of the box" only with certain languages
|
||||
out of all the languages available from the DrScheme languages
|
||||
menu. For example, the macro stepper is disabled for the teaching
|
||||
languages.
|
||||
|
||||
An implementor of a new DrScheme language can designate their language
|
||||
"macro-steppable" by overriding the 'enable-macro-stepper?' method of
|
||||
their implementation of 'drscheme:language:language<%>'. The default
|
||||
implementation in the mixin provided by
|
||||
'drscheme:language:get-default-mixin' returns false; override this
|
||||
method to return true if the macro stepper button should be shown for
|
||||
this language.
|
||||
|
||||
Note: There is currently no way to customize the behavior of the macro
|
||||
stepper for different languages. When enabled, the macro stepper sees
|
||||
exactly those terms that pass through the 'current-eval' handler.
|
||||
Loading…
Reference in New Issue
Block a user