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\chapter{ML Functions in the prettyp Library}\input{entries-intro}\DOC{Address} \TYPE {\small\verb%Address : (int list -> address)%}\egroup \SYNOPSIS Type constructor for sub-tree addresses. \DESCRIBE {\small\verb%Address il%} denotes the address of a sub-tree within a tree. The integer list {\small\verb%il%} is the path that has to be followed from the root node of the tree in order to reach the sub-tree. \FAILURE Never fails. \EXAMPLE The ML value {\small\verb%Address [1;2]%} is the address within the tree: {\par\samepage\setseps\small \begin{verbatim} a / \ b c / \ \ d e f / \ g h \end{verbatim} } \noindent of the sub-tree: {\par\samepage\setseps\small \begin{verbatim} e / \ g h \end{verbatim} } \noindent The sub-tree is the second child of the first child of the main tree. \USES Sub-tree addresses are maintained as far as possible during the pretty-printing process. They can thus be used to determine which sub-tree of the original parse-tree was used to generate some specified part of the pretty-printed text. \SEEALSO No_address. \ENDDOC \DOC{All\_types} \TYPE {\small\verb%All_types : type_selection%}\egroup \SYNOPSIS Value used to control the amount of type information included in the print-tree of a term. \DESCRIBE {\small\verb%All_types%} is a value used to instruct the term-to-print-tree conversion function to include type information in the tree for every variable and constant in the term. \SEEALSO No_types, Hidden_types, Useful_types, term_to_print_tree. \ENDDOC \DOC{apply0} \TYPE {\small\verb%apply0 : (* -> (string # int) list -> print_binding -> *)%}\egroup \SYNOPSIS Function for constructing environment accessing functions. \DESCRIBE {\small\verb%apply0%} is a higher-order function which can be used to simplify the ML code required for user-defined pretty-printer environment accessing functions. Instead of having to mention the parameter list and binding explicitly as in: {\par\samepage\setseps\small \begin{verbatim} \params. \pbind. f \end{verbatim} } \noindent one can use {\small\verb%apply0%}: {\par\samepage\setseps\small \begin{verbatim} apply0 f \end{verbatim} } \FAILURE Cannot fail when given only one argument. However, the resulting function may fail. This will depend on the value of the argument. \EXAMPLE A function for testing whether the parameter {\small\verb%test%}' has value 1 can be written as: {\par\samepage\setseps\small \begin{verbatim} apply2 (curry $=) (bound_number test) (apply0 1) \end{verbatim} } \noindent instead of: {\par\samepage\setseps\small \begin{verbatim} \params. \pbind. (bound_number test params pbind) = 1 \end{verbatim} } \noindent In this example it is not clear that use of {\small\verb%apply0%} and {\small\verb%apply2%} is beneficial. However, it illustrates their usage. \SEEALSO apply1, apply2. \ENDDOC \DOC{apply1} {\small \begin{verbatim} apply1 : ((* -> **) -> ((string # int) list -> print_binding -> *) -> ((string # int) list -> print_binding -> **)) \end{verbatim} }\egroup \SYNOPSIS Function for constructing environment accessing functions. \DESCRIBE {\small\verb%apply1%} is a higher-order function which can be used to simplify the ML code required for user-defined pretty-printer environment accessing functions. Instead of having to mention the parameter list and binding explicitly as in: {\par\samepage\setseps\small \begin{verbatim} \params. \pbind. f (val params pbind) \end{verbatim} } \noindent one can use {\small\verb%apply1%}: {\par\samepage\setseps\small \begin{verbatim} apply1 f val \end{verbatim} } \FAILURE Cannot fail when given no more than two arguments. However, the resulting function may fail. This will depend on the values of the arguments. \EXAMPLE Suppose a function is required which evaluates the length of the node-name bound to the metavariable {\small\verb%***x%}. The ML code for this is: {\par\samepage\setseps\small \begin{verbatim} \params. \pbind. (length o explode) (bound_name x params pbind) \end{verbatim} } \noindent The function takes a parameter list and a binding as arguments. It uses these to find the node-name bound to the metavariable with name {\small\verb%x%}'. The resulting string is then exploded into a list of single character strings and the length of this list is computed. Using {\small\verb%apply1%}, the code can be written more simply as: {\par\samepage\setseps\small \begin{verbatim} apply1 (length o explode) (bound_name x) \end{verbatim} } \SEEALSO apply0, apply2. \ENDDOC \DOC{apply2} {\small \begin{verbatim} apply2 : ((* -> ** -> ***) -> ((string # int) list -> print_binding -> *) -> ((string # int) list -> print_binding -> **) -> ((string # int) list -> print_binding -> ***)) \end{verbatim} }\egroup \SYNOPSIS Function for constructing environment accessing functions. \DESCRIBE {\small\verb%apply2%} is a higher-order function which can be used to simplify the ML code required for user-defined pretty-printer environment accessing functions. Instead of having to mention the parameter list and binding explicitly as in: {\par\samepage\setseps\small \begin{verbatim} \params. \pbind. f (val1 params pbind) (val2 params pbind) \end{verbatim} } \noindent one can use {\small\verb%apply2%}: {\par\samepage\setseps\small \begin{verbatim} apply2 f val1 val2 \end{verbatim} } \FAILURE Cannot fail when given no more than three arguments. However, the resulting function may fail. This will depend on the values of the arguments. \EXAMPLE A function for testing whether the parameter {\small\verb%test%}' has value 1 can be written as: {\par\samepage\setseps\small \begin{verbatim} apply2 (curry$=) (bound_number test) (\params. \pbind. 1) \end{verbatim} } \noindent instead of: {\par\samepage\setseps\small \begin{verbatim} \params. \pbind. (bound_number test params pbind) = 1 \end{verbatim} } \noindent In this example it is not clear that use of {\small\verb%apply2%} is beneficial. However, it illustrates its usage. \SEEALSO apply0, apply1. \ENDDOC \DOC{bound\_child} {\small \begin{verbatim} bound_child : (string -> (string # int) list -> print_binding -> print_tree) \end{verbatim} }\egroup \SYNOPSIS Obtains the print-tree bound to a pretty-printer metavariable. \DESCRIBE {\small\verb%bound_child%} can be used to obtain the data item bound to a named metavariable. It takes the name of a metavariable (less the preceding {\small\verb%*%}, {\small\verb%**%}, or {\small\verb%***%}) as its first argument and returns a function of type: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> print_tree \end{verbatim} } \noindent When given the current environment as arguments, this function yields the print-tree bound to the specified metavariable. The parameter list is not used, but is present for consistency. \FAILURE The function fails if the specified metavariable is not bound to a print-tree. It also fails if the metavariable cannot be found in the binding. \SEEALSO bound_children, bound_name, bound_names, is_a_member_of, bound_number, bound_context. \ENDDOC \DOC{bound\_children} {\small \begin{verbatim} bound_children : (string -> (string # int) list -> print_binding -> print_tree list) \end{verbatim} }\egroup \SYNOPSIS Obtains the print-trees bound to a pretty-printer metavariable. \DESCRIBE {\small\verb%bound_children%} can be used to obtain the data item bound to a named metavariable. It takes the name of a metavariable (less the preceding {\small\verb%*%}, {\small\verb%**%}, or {\small\verb%***%}) as its first argument and returns a function of type: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> print_tree list \end{verbatim} } \noindent When given the current environment as arguments, this function yields the list of print-trees bound to the specified metavariable. The parameter list is not used, but is present for consistency. \FAILURE The function fails if the specified metavariable is not bound to a list of print-trees. It also fails if the metavariable cannot be found in the binding. \SEEALSO bound_child, bound_name, bound_names, is_a_member_of, bound_number, bound_context. \ENDDOC \DOC{bound\_context} \TYPE {\small\verb%bound_context : ((string # int) list -> print_binding -> string)%}\egroup \SYNOPSIS Obtains the value of the current context from the pretty-printer environment. \DESCRIBE To make it easier to extract the value of the current context from its rather contorted representation in the parameter list, there is a function called {\small\verb%bound_context%}. When presented with the current environment by way of its arguments, {\small\verb%bound_context%} returns the character string representing the current context. The binding is not used, but is present for consistency. \FAILURE The function will not fail unless it is given an invalid parameter list. \SEEALSO is_a_member_of, bound_name, bound_names, bound_child, bound_children, bound_number. \ENDDOC \DOC{bound\_name} \TYPE {\small\verb%bound_name : (string -> (string # int) list -> print_binding -> string)%}\egroup \SYNOPSIS Obtains the node-name bound to a pretty-printer metavariable. \DESCRIBE {\small\verb%bound_name%} can be used to obtain the data item bound to a named metavariable. It takes the name of a metavariable (less the preceding {\small\verb%*%}, {\small\verb%**%}, or {\small\verb%***%}) as its first argument and returns a function of type: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> string \end{verbatim} } \noindent When given the current environment as arguments, this function yields the node-name bound to the specified metavariable. The parameter list is not used, but is present for consistency. \FAILURE The function fails if the specified metavariable is not bound to a single node-name. It also fails if the metavariable cannot be found in the binding. \SEEALSO bound_names, bound_child, bound_children, is_a_member_of, bound_number, bound_context. \ENDDOC \DOC{bound\_names} {\small \begin{verbatim} bound_names : (string -> (string # int) list -> print_binding -> string list) \end{verbatim} }\egroup \SYNOPSIS Obtains the node-names bound to a pretty-printer metavariable. \DESCRIBE {\small\verb%bound_names%} can be used to obtain the data item bound to a named metavariable. It takes the name of a metavariable (less the preceding {\small\verb%*%}, {\small\verb%**%}, or {\small\verb%***%}) as its first argument and returns a function of type: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> string list \end{verbatim} } \noindent When given the current environment as arguments, this function yields the list of node-names bound to the specified metavariable. The parameter list is not used, but is present for consistency. \FAILURE The function fails if the specified metavariable is not bound to a list of node-names. It also fails if the metavariable cannot be found in the binding. \SEEALSO bound_name, bound_child, bound_children, is_a_member_of, bound_number, bound_context. \ENDDOC \DOC{bound\_number} \TYPE {\small\verb%bound_number : (string -> print_int_exp)%}\egroup \SYNOPSIS Obtains the value bound to a pretty-printer parameter. \DESCRIBE {\small\verb%bound_number%} takes the name of a pretty-printer parameter as its first argument (a string) and returns a function of type: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> int \end{verbatim} } \noindent This function yields the integer value associated with the parameter, when it is presented with an environment via its two arguments. The binding is not used, but is present for consistency. \FAILURE The function fails if the parameter is not present in the parameter list. \SEEALSO is_a_member_of, bound_name, bound_names, bound_child, bound_children, bound_context. \ENDDOC \DOC{get\_margin} \TYPE {\small\verb%get_margin : (void -> int)%}\egroup \SYNOPSIS Returns the limit on the width of the output produced by the standard HOL pretty-printer. \FAILURE Never fails. \EXAMPLE {\par\samepage\setseps\small \begin{verbatim} #get_margin ();; 72 : int \end{verbatim} } \SEEALSO set_margin. \ENDDOC \DOC{Hidden\_types} \TYPE {\small\verb%Hidden_types : type_selection%}\egroup \SYNOPSIS Value used to control the amount of type information included in the print-tree of a term. \DESCRIBE {\small\verb%Hidden_types%} is a value used to instruct the term-to-print-tree conversion function as to how much type information to include in the tree. Type information is only included for variables which, although free, without type information appear to be bound. An example of such a variable is {\small\verb%"x:num"%} in the term: {\par\samepage\setseps\small \begin{verbatim} "\(x:bool). (x:num)" \end{verbatim} } \noindent Without types, this term appears as {\small\verb%"\x. x"%}. However, the two occurrences of {\small\verb%x%} are different. \SEEALSO No_types, Useful_types, All_types, term_to_print_tree. \ENDDOC \DOC{hol\_rules\_fun} \TYPE {\small\verb%hol_rules_fun : print_rule_function%}\egroup \SYNOPSIS Pretty-printing rules (as a function) for HOL types, terms and theorems. \FAILURE Fails if none of the rules match the input. However, this function should not be applied by hand'; it should only be used as an argument to one of the pretty-printing functions. \SEEALSO hol_type_rules_fun, hol_term_rules_fun, hol_thm_rules_fun, raw_tree_rules_fun, then_try, pretty_print, pp, pp_write. \ENDDOC \DOC{hol\_term\_rules\_fun} \TYPE {\small\verb%hol_term_rules_fun : print_rule_function%}\egroup \SYNOPSIS Pretty-printing rules (as a function) for HOL terms. {\small\verb%hol_type_rules_fun%} is required for {\small\verb%hol_term_rules_fun%} to function correctly. \FAILURE Fails if none of the rules match the input. However, this function should not be applied by hand'; it should only be used as an argument to one of the pretty-printing functions. \SEEALSO hol_type_rules_fun, hol_thm_rules_fun, hol_rules_fun, raw_tree_rules_fun, then_try, pretty_print, pp, pp_write. \ENDDOC \DOC{hol\_thm\_rules\_fun} \TYPE {\small\verb%hol_thm_rules_fun : print_rule_function%}\egroup \SYNOPSIS Pretty-printing rules (as a function) for HOL theorems. The rules {\small\verb%hol_type_rules_fun%} and {\small\verb%hol_term_rules_fun%} are required for {\small\verb%hol_thm_rules_fun%} to function correctly. \FAILURE Fails if none of the rules match the input. However, this function should not be applied by hand'; it should only be used as an argument to one of the pretty-printing functions. \SEEALSO hol_type_rules_fun, hol_term_rules_fun, hol_rules_fun, raw_tree_rules_fun, then_try, pretty_print, pp, pp_write. \ENDDOC \DOC{hol\_type\_rules\_fun} \TYPE {\small\verb%hol_type_rules_fun : print_rule_function%}\egroup \SYNOPSIS Pretty-printing rules (as a function) for HOL types. \FAILURE Fails if none of the rules match the input. However, this function should not be applied by hand'; it should only be used as an argument to one of the pretty-printing functions. \SEEALSO hol_term_rules_fun, hol_thm_rules_fun, hol_rules_fun, raw_tree_rules_fun, then_try, pretty_print, pp, pp_write. \ENDDOC \DOC{is\_a\_member\_of} \TYPE {\small\verb%$is_a_member_of : (string -> string list -> print_test)%}\egroup \SYNOPSIS Function for testing a node-name metavariable in a pretty-printing rule. \DESCRIBE {\small\verb%is_a_member_of%} forms a {\small\verb%print_test%} which yields {\small\verb%true%} only if the metavariable whose name is the first argument to {\small\verb%is_a_member_of%} is bound to a node-name which appears in the second argument. This evaluation to a Boolean value is only performed when the {\small\verb%print_test%} is applied to a parameter list and a binding. \FAILURE The function fails if the metavariable named is bound to anything other than a single node-name. \EXAMPLE An example of the use of this function is the rule: {\par\samepage\setseps\small \begin{verbatim} ''::***node(*,*) where {node is_a_member_of [plus;minus;mult;div]} -> [ ***node]; \end{verbatim} } \SEEALSO bound_number, bound_name, bound_names, bound_child, bound_children, bound_context. \ENDDOC \DOC{max\_term\_prec} \TYPE {\small\verb%max_term_prec : int%}\egroup \SYNOPSIS Lowest precedence (maximum value) used by the pretty-printer for HOL function constants and syntactic constructs in terms. \SEEALSO min_term_prec, term_prec. \ENDDOC \DOC{max\_type\_prec} \TYPE {\small\verb%max_type_prec : int%}\egroup \SYNOPSIS Lowest precedence (maximum value) used by the pretty-printer for HOL type operators. \SEEALSO min_type_prec, type_prec. \ENDDOC \DOC{min\_term\_prec} \TYPE {\small\verb%min_term_prec : int%}\egroup \SYNOPSIS Highest precedence (minimum value) used by the pretty-printer for HOL function constants and syntactic constructs in terms. \SEEALSO max_term_prec, term_prec. \ENDDOC \DOC{min\_type\_prec} \TYPE {\small\verb%min_type_prec : int%}\egroup \SYNOPSIS Highest precedence (minimum value) used by the pretty-printer for HOL type operators. \SEEALSO max_type_prec, type_prec. \ENDDOC \DOC{new\_child} {\small \begin{verbatim} new_child : ((print_tree -> print_tree) -> string -> (string # int) list -> print_binding -> metavar_binding) \end{verbatim} }\egroup \SYNOPSIS Function for transforming a print-tree bound to a metavariable. \DESCRIBE Within the metavariable transformation part of a pretty-printing rule, a typical requirement is to declare' a new metavariable to be bound to the result of performing a transformation on a single existing metavariable. The type of function required is: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> metavar_binding \end{verbatim} } \noindent There are four functions available to facilitate this, corresponding to the four different types of data which can be bound to a metavariable. {\small\verb%new_child%} is the function for use when the data is a single print-tree. The first argument is the transformation function. The second argument is the name of the metavariable which is bound to the value to be transformed. When provided with these arguments and a pretty-printer environment, {\small\verb%new_child%} extracts the item bound to the named metavariable and then applies the transformation function to it. The result is then made into a form suitable for binding to a metavariable, that is it is made into an object of type {\small\verb%metavar_binding%}. \FAILURE {\small\verb%new_child%} fails if the named metavariable does not exist or is bound to an item of the wrong type. \SEEALSO new_children, new_name, new_names, bound_child. \ENDDOC \DOC{new\_children} {\small \begin{verbatim} new_children : (((print_tree # address) list -> (print_tree # address) list) -> string -> (string # int) list -> print_binding -> metavar_binding) \end{verbatim} }\egroup \SYNOPSIS Function for transforming a list of print-trees bound to a metavariable. \DESCRIBE Within the metavariable transformation part of a pretty-printing rule, a typical requirement is to declare' a new metavariable to be bound to the result of performing a transformation on a single existing metavariable. The type of function required is: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> metavar_binding \end{verbatim} } \noindent There are four functions available to facilitate this, corresponding to the four different types of data which can be bound to a metavariable. {\small\verb%new_children%} is the function for use when the data is a list of print-trees. The first argument is the transformation function. The second argument is the name of the metavariable which is bound to the value to be transformed. When provided with these arguments and a pretty-printer environment, {\small\verb%new_children%} extracts the item bound to the named metavariable and then applies the transformation function to it. The result is then made into a form suitable for binding to a metavariable, that is it is made into an object of type {\small\verb%metavar_binding%}. Note that the transformation function has to deal with sub-tree addresses in addition to the print-trees. If the transformation function is polymorphic, as is for example a function to reverse the list, this will not cause any difficulties. The addresses have to be dealt with by the transformation function because the system cannot know how to re-assign addresses to the values in the result list. \FAILURE {\small\verb%new_children%} fails if the named metavariable does not exist or is bound to an item of the wrong type. \SEEALSO new_child, new_name, new_names, bound_children. \ENDDOC \DOC{new\_name} {\small \begin{verbatim} new_name : ((string -> string) -> string -> (string # int) list -> print_binding -> metavar_binding) \end{verbatim} }\egroup \SYNOPSIS Function for transforming a node-name bound to a metavariable. \DESCRIBE Within the metavariable transformation part of a pretty-printing rule, a typical requirement is to declare' a new metavariable to be bound to the result of performing a transformation on a single existing metavariable. The type of function required is: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> metavar_binding \end{verbatim} } \noindent There are four functions available to facilitate this, corresponding to the four different types of data which can be bound to a metavariable. {\small\verb%new_name%} is the function for use when the data is a single node-name. The first argument is the transformation function. The second argument is the name of the metavariable which is bound to the value to be transformed. When provided with these arguments and a pretty-printer environment, {\small\verb%new_name%} extracts the item bound to the named metavariable and then applies the transformation function to it. The result is then made into a form suitable for binding to a metavariable, that is it is made into an object of type {\small\verb%metavar_binding%}. \FAILURE {\small\verb%new_name%} fails if the named metavariable does not exist or is bound to an item of the wrong type. \SEEALSO new_names, new_child, new_children, bound_name. \ENDDOC \DOC{new\_names} {\small \begin{verbatim} new_names : (((string # address) list -> (string # address) list) -> string -> (string # int) list -> print_binding -> metavar_binding) \end{verbatim} }\egroup \SYNOPSIS Function for transforming a list of node-names bound to a metavariable. \DESCRIBE Within the metavariable transformation part of a pretty-printing rule, a typical requirement is to declare' a new metavariable to be bound to the result of performing a transformation on a single existing metavariable. The type of function required is: {\par\samepage\setseps\small \begin{verbatim} (string # int) list -> print_binding -> metavar_binding \end{verbatim} } \noindent There are four functions available to facilitate this, corresponding to the four different types of data which can be bound to a metavariable. {\small\verb%new_names%} is the function for use when the data is a list of node-names. The first argument is the transformation function. The second argument is the name of the metavariable which is bound to the value to be transformed. When provided with these arguments and a pretty-printer environment, {\small\verb%new_names%} extracts the item bound to the named metavariable and then applies the transformation function to it. The result is then made into a form suitable for binding to a metavariable, that is it is made into an object of type {\small\verb%metavar_binding%}. Note that the transformation function has to deal with sub-tree addresses in addition to the node-names. If the transformation function is polymorphic, as is for example a function to reverse the list, this will not cause any difficulties. The addresses have to be dealt with by the transformation function because the system cannot know how to re-assign addresses to the values in the result list. \FAILURE {\small\verb%new_names%} fails if the named metavariable does not exist or is bound to an item of the wrong type. \SEEALSO new_name, new_child, new_children, bound_names. \ENDDOC \DOC{No\_address} \TYPE {\small\verb%No_address : address%}\egroup \SYNOPSIS Type constructor for sub-tree addresses. \DESCRIBE {\small\verb%No_address%} is used to indicate that there is no valid address information for a sub-tree. \SEEALSO Address. \ENDDOC \DOC{No\_types} \TYPE {\small\verb%No_types : type_selection%}\egroup \SYNOPSIS Value used to control the amount of type information included in the print-tree of a term. \DESCRIBE {\small\verb%No_types%} is a value used to instruct the term-to-print-tree conversion function to include no type information in the tree. \SEEALSO Hidden_types, Useful_types, All_types, term_to_print_tree. \ENDDOC \DOC{pp\_convert\_all\_thm} \TYPE {\small\verb%pp_convert_all_thm : (thm -> print_tree)%}\egroup \SYNOPSIS Function for converting a HOL theorem into a print-tree. \DESCRIBE {\small\verb%pp_convert_all_thm%} converts a theorem into a print-tree. The hypotheses (assumptions) of the theorem are included in the print-tree. Instances of the HOL constant {\small\verb%UNCURRY%} in the theorem are converted into an appropriate use of ordered pairs in the print-tree. The amount of type information included in the print-tree is determined by the value of the HOL system flag {\small\verb%show_types%}. If {\small\verb%show_types%} is {\small\verb%true%}, then useful' types are included in the print-tree. Otherwise, only hidden' types are included. Useful' type information is type information on the bound variables of abstractions and on one occurrence of every free variable. Type information is only included for constants if the constant is a function and it is not fully applied. Hidden' types are rare. They only occur on variables which, although free, without type information appear to be bound. \FAILURE Never fails. \SEEALSO pp_convert_thm, pp_convert_type, pp_convert_term, thm_to_print_tree. \ENDDOC \DOC{pp\_convert\_term} \TYPE {\small\verb%pp_convert_term : (term -> print_tree)%}\egroup \SYNOPSIS Function for converting a HOL term into a print-tree. \DESCRIBE {\small\verb%pp_convert_term%} converts a term into a print-tree. Instances of the HOL constant {\small\verb%UNCURRY%} in the term are converted into an appropriate use of ordered pairs in the print-tree. The amount of type information included in the print-tree is determined by the value of the HOL system flag {\small\verb%show_types%}. If {\small\verb%show_types%} is {\small\verb%true%}, then useful' types are included in the print-tree. Otherwise, only hidden' types are included. Useful' type information is type information on the bound variables of abstractions and on one occurrence of every free variable. Type information is only included for constants if the constant is a function and it is not fully applied. Hidden' types are rare. They only occur on variables which, although free, without type information appear to be bound. \FAILURE Never fails. \SEEALSO pp_convert_type, pp_convert_thm, pp_convert_all_thm, term_to_print_tree. \ENDDOC \DOC{pp\_convert\_thm} \TYPE {\small\verb%pp_convert_thm : (thm -> print_tree)%}\egroup \SYNOPSIS Function for converting a HOL theorem into a print-tree. \DESCRIBE {\small\verb%pp_convert_thm%} converts a theorem into a print-tree. The hypotheses (assumptions) of the theorem are not included in the print-tree. Instances of the HOL constant {\small\verb%UNCURRY%} in the theorem are converted into an appropriate use of ordered pairs in the print-tree. The amount of type information included in the print-tree is determined by the value of the HOL system flag {\small\verb%show_types%}. If {\small\verb%show_types%} is {\small\verb%true%}, then useful' types are included in the print-tree. Otherwise, only hidden' types are included. Useful' type information is type information on the bound variables of abstractions and on one occurrence of every free variable. Type information is only included for constants if the constant is a function and it is not fully applied. Hidden' types are rare. They only occur on variables which, although free, without type information appear to be bound. \FAILURE Never fails. \SEEALSO pp_convert_all_thm, pp_convert_type, pp_convert_term, thm_to_print_tree. \ENDDOC \DOC{pp\_convert\_type} \TYPE {\small\verb%pp_convert_type : (type -> print_tree)%}\egroup \SYNOPSIS Function for converting a HOL type into a print-tree. \DESCRIBE {\small\verb%pp_convert_type%} has an identical specification to {\small\verb%type_to_print_tree%}. \FAILURE Never fails. \SEEALSO type_to_print_tree, pp_convert_term, pp_convert_thm, pp_convert_all_thm. \ENDDOC \DOC{pp} {\small \begin{verbatim} pp : (print_rule_function -> string -> (string # int) list -> print_tree -> void) \end{verbatim} }\egroup \SYNOPSIS One of the main pretty-printing functions. For use with the standard HOL pretty-printer. \DESCRIBE {\small\verb%pp%} invokes the pretty-printer. It can be used for merging output with text produced by the standard HOL pretty-printer. Instead of ending each line of text by printing a new-line, it sends its output to the standard HOL printer in the form of a pretty-printing block. The arguments to the function are: (1) pretty-printing rules expressed as a function, (2) the initial context, (3) initial parameters, (4) tree to be printed. {\small\verb%pp%} uses as its maximum width the width for the standard HOL printer, as specified by the function {\small\verb%set_margin%}. The initial offset from the left margin is taken to be zero. \FAILURE Failure or incorrect behaviour can be caused by mistakes in the pretty-printing rules or by inappropriate arguments to the printing function. The most common errors are use of uninitialised parameters and reference to unknown metavariables. The latter are due to metavariables appearing in the format of a rule, but not in the pattern. Errors also occur if a metavariable is used in a place inappropriate for the value it is bound to. An example of this is an attempt to compare a string with a metavariable that is bound to a tree rather than a node-name. Use of negative indentations in formats may cause text to overflow the left margin, and an exception to be raised. Any user defined function may also cause a run-time error. The printing functions have been designed to trap exceptions and to print {\small\verb%*error*%}. This does not indicate what caused the error, but it may give some indication of where the error occurred. However, this is not the main reason for trapping exceptions. The ML directive {\small\verb%top_print%} installs a user print function. If an exception is raised within this function, it does not appear at the top-level of ML. Instead, an obscure Lisp error is produced. Since the pretty-printing functions are normally used with {\small\verb%top_print%}, it is best to avoid raising exceptions. For this reason the printing functions display {\small\verb%*error*%} instead. \SEEALSO pretty_print, pp_write. \ENDDOC \DOC{pp\_print\_all\_thm} \TYPE {\small\verb%pp_print_all_thm : (thm -> void)%}\egroup \SYNOPSIS Print function for HOL theorems. Simulates the HOL system function {\small\verb%print_all_thm%}. \FAILURE Never fails. \SEEALSO pp_print_thm, pp_print_type, pp_print_term. \ENDDOC \DOC{pp\_print\_term} \TYPE {\small\verb%pp_print_term : (term -> void)%}\egroup \SYNOPSIS Print function for HOL terms. Simulates the HOL system function {\small\verb%print_term%}. \FAILURE Never fails. \SEEALSO pp_print_type, pp_print_thm, pp_print_all_thm. \ENDDOC \DOC{pp\_print\_theory} \TYPE {\small\verb%pp_print_theory : (string -> void)%}\egroup \SYNOPSIS Print function for HOL theories. \DESCRIBE {\small\verb%pp_print_theory%} simulates the HOL system function {\small\verb%print_theory%} using the pretty-printer library. The function takes a theory-segment name as argument. The following information is displayed: the parents of the theory, types defined within the theory, constants of the theory, the binders and infixes (subsets of the constants), the axioms, the definitions, and the derived theorems. \FAILURE Fails if the named theory does not exist or is not an ancestor of the current theory. \SEEALSO pp_print_type, pp_print_term, pp_print_thm, pp_print_all_thm. \ENDDOC \DOC{pp\_print\_thm} \TYPE {\small\verb%pp_print_thm : (thm -> void)%}\egroup \SYNOPSIS Print function for HOL theorems. Simulates the HOL system function {\small\verb%print_thm%}. \FAILURE Never fails. \SEEALSO pp_print_all_thm, pp_print_type, pp_print_term. \ENDDOC \DOC{pp\_print\_type} \TYPE {\small\verb%pp_print_type : (type -> void)%}\egroup \SYNOPSIS Print function for HOL types. Simulates the HOL system function {\small\verb%print_type%}. \FAILURE Never fails. \SEEALSO pp_print_term, pp_print_thm, pp_print_all_thm. \ENDDOC \DOC{PP\_to\_ML} \TYPE {\small\verb%PP_to_ML : (bool -> string -> string -> void)%}\egroup \SYNOPSIS Function to compile pretty-printing rules into ML datastructures. \DESCRIBE The function {\small\verb%PP_to_ML%} invokes the parser for the pretty-printing language. Its first argument indicates whether or not the output is to be appended to the destination file. If the argument is {\small\verb%false%} and the destination file existed previously, the file is overwritten. The second and third arguments specify the names of the source and destination files respectively. For example, the ML function call: {\par\samepage\setseps\small \begin{verbatim} PP_to_ML false xxxx.pp ;; \end{verbatim} } \noindent compiles the file {\small\verb%xxxx.pp%} to a file called {\small\verb%xxxx_pp.ml%}, overwriting any previous version. The {\small\verb%.pp%}' extension can be omitted. So, the following has precisely the same effect as the previous command': {\par\samepage\setseps\small \begin{verbatim} PP_to_ML false xxxx ;; \end{verbatim} } \noindent If the last argument is anything other than the empty string, it is used as the name of the destination file. So, {\par\samepage\setseps\small \begin{verbatim} PP_to_ML false xxxx test.ml;; \end{verbatim} } \noindent compiles the file {\small\verb%xxxx.pp%} to the file {\small\verb%test.ml%}. \FAILURE The compiler may fail to parse the source code. In this case the error message specifies the kind of symbol the compiler was expecting and the kind of symbol it received. In addition, the compiler displays a few lines of the source file following the point at which the failure occurred. This should facilitate the location of the fault. The second kind of error occurs after the parse has completed successfully. At this point the compiler is converting the parse-tree into ML. Faults at this point are due to additional restrictions not being met, and the error messages are correspondingly ad hoc. The part of the parse-tree under conversion is printed in the pretty-printing language. This may or may not be helpful, depending on the size of the tree. \ENDDOC \DOC{pp\_write} {\small \begin{verbatim} pp_write : (string -> int -> int -> print_rule_function -> string -> (string # int) list -> print_tree -> void) \end{verbatim} }\egroup \SYNOPSIS One of the main pretty-printing functions. Function for printing to files. \DESCRIBE {\small\verb%pp_write%} invokes the pretty-printer. The arguments to this function are: (1) file handle (port) of the file to be written to, (2) maximum width of output permitted, (3) initial offset from left margin, (4) pretty-printing rules expressed as a function, (5) the initial context, (6) initial parameters, (7) tree to be printed. \FAILURE Failure or incorrect behaviour can be caused by mistakes in the pretty-printing rules or by inappropriate arguments to the printing function. The most common errors are use of uninitialised parameters and reference to unknown metavariables. The latter are due to metavariables appearing in the format of a rule, but not in the pattern. Errors also occur if a metavariable is used in a place inappropriate for the value it is bound to. An example of this is an attempt to compare a string with a metavariable that is bound to a tree rather than a node-name. Use of negative indentations in formats may cause text to overflow the left margin, and an exception to be raised. Any user defined function may also cause a run-time error. The printing functions have been designed to trap exceptions and to print {\small\verb%*error*%}. This does not indicate what caused the error, but it may give some indication of where the error occurred. However, this is not the main reason for trapping exceptions. The ML directive {\small\verb%top_print%} installs a user print function. If an exception is raised within this function, it does not appear at the top-level of ML. Instead, an obscure Lisp error is produced. Since the pretty-printing functions are normally used with {\small\verb%top_print%}, it is best to avoid raising exceptions. For this reason the printing functions display {\small\verb%*error*%} instead. \SEEALSO pretty_print, pp. \ENDDOC \DOC{pretty\_print} {\small \begin{verbatim} pretty_print : (int -> int -> print_rule_function -> string -> (string # int) list -> print_tree -> void) \end{verbatim} }\egroup \SYNOPSIS One of the main pretty-printing functions. This one writes directly to the terminal, independently of the standard HOL printer. \DESCRIBE {\small\verb%pretty_print%} invokes the pretty-printer. The arguments to this function are: (1) maximum width of output permitted, (2) initial offset from left margin, (3) pretty-printing rules expressed as a function, (4) the initial context, (5) initial parameters, (6) tree to be printed. \FAILURE Failure or incorrect behaviour can be caused by mistakes in the pretty-printing rules or by inappropriate arguments to the printing function. The most common errors are use of uninitialised parameters and reference to unknown metavariables. The latter are due to metavariables appearing in the format of a rule, but not in the pattern. Errors also occur if a metavariable is used in a place inappropriate for the value it is bound to. An example of this is an attempt to compare a string with a metavariable that is bound to a tree rather than a node-name. Use of negative indentations in formats may cause text to overflow the left margin, and an exception to be raised. Any user defined function may also cause a run-time error. The printing functions have been designed to trap exceptions and to print {\small\verb%*error*%}. This does not indicate what caused the error, but it may give some indication of where the error occurred. However, this is not the main reason for trapping exceptions. The ML directive {\small\verb%top_print%} installs a user print function. If an exception is raised within this function, it does not appear at the top-level of ML. Instead, an obscure Lisp error is produced. Since the pretty-printing functions are normally used with {\small\verb%top_print%}, it is best to avoid raising exceptions. For this reason the printing functions display {\small\verb%*error*%} instead. \SEEALSO pp, pp_write. \ENDDOC \DOC{Print\_node} \TYPE {\small\verb%Print_node : ((string # print_tree list) -> print_tree)%}\egroup \SYNOPSIS Constructor function for print-trees (parse-trees). \DESCRIBE {\small\verb%Print_node%} takes a node label and a list of sub-trees and uses them to construct a new print-tree. Leaf nodes have an empty sub-tree (child) list. \FAILURE Never fails. \SEEALSO print_tree_name, print_tree_children. \ENDDOC \DOC{print\_tree\_children} \TYPE {\small\verb%print_tree_children : (print_tree -> print_tree list)%}\egroup \SYNOPSIS Function to extract the sub-trees (children) of the root node of a print-tree. \FAILURE Never fails. \SEEALSO print_tree_name, Print_node. \ENDDOC \DOC{print\_tree\_name} \TYPE {\small\verb%print_tree_name : (print_tree -> string)%}\egroup \SYNOPSIS Function to extract the name (label) of the root node of a print-tree. \FAILURE Never fails. \SEEALSO print_tree_children, Print_node. \ENDDOC \DOC{raw\_tree\_rules\_fun} \TYPE {\small\verb%raw_tree_rules_fun : print_rule_function%}\egroup \SYNOPSIS Pretty-printing rules (as a function) for raw print-trees (parse-trees). \DESCRIBE In the event of no pretty-printing rules matching the tree to be printed, a default set of rules are used. These rules always match, and the output generated is a textual representation of the structure of the tree. The default rules are available to the user as {\small\verb%raw_tree_rules_fun%}. \FAILURE Never fails. \SEEALSO hol_type_rules_fun, hol_term_rules_fun, hol_thm_rules_fun, hol_rules_fun, then_try, pretty_print, pp, pp_write. \ENDDOC \DOC{term\_prec} \TYPE {\small\verb%term_prec : (string -> int)%}\egroup \SYNOPSIS Precedence table for HOL terms (as a function). \DESCRIBE {\small\verb%term_prec%} is a function which given the name of a HOL function constant, returns the precedence used by the pretty-printer. The precedences of abstractions ({\small\verb%\\%}) and type annotations ({\small\verb%:%}) are also included. \FAILURE Never fails. \SEEALSO min_term_prec, max_term_prec, type_prec. \ENDDOC \DOC{term\_to\_print\_tree} \TYPE {\small\verb%term_to_print_tree : (bool -> type_selection -> term -> print_tree)%}\egroup \SYNOPSIS Function for converting a HOL term into a print-tree. \DESCRIBE The first argument to {\small\verb%term_to_print_tree%} is a flag. If the flag is {\small\verb%true%}, the function converts instances of the HOL constant {\small\verb%UNCURRY%} in the term into an appropriate use of ordered pairs in the print-tree. If the flag is {\small\verb%false%}, {\small\verb%UNCURRY%} is treated in the same way as any other HOL constant. The conversion is necessary because the representation of tuples of bound variables in a HOL term is so unlike the syntax of the tuples that the pretty-printer cannot handle them. So, normally, the flag should be set to {\small\verb%true%}. The second argument to {\small\verb%term_to_print_tree%} controls the amount of type information included in the print-tree of the term. If {\small\verb%No_types%} is given as the argument, then the print-tree will contain no type information. If {\small\verb%All_types%} is given as the argument, the tree will contain type information for every variable and constant. Use of {\small\verb%Useful_types%} instructs {\small\verb%term_to_print_tree%} to attach type information to the bound variables of abstractions, and to one occurrence of every free variable. Type information is only included for constants if the constant is a function and it is not fully applied. So, the equals sign in {\small\verb%"1 = 2"%} would not be adorned with type information, but in {\small\verb%"$= 1"%} it would be. Finally, using {\small\verb%Hidden_types%} as the second argument to {\small\verb%term_to_print_tree%} causes type information to be attached only to variables which, although free, without type information appear to be bound. An example of such a variable is {\small\verb%"x:num"%} in the term: {\par\samepage\setseps\small \begin{verbatim} "\(x:bool). (x:num)" \end{verbatim} } \noindent Without types, this term appears as {\small\verb%"\x. x"%}. However, the two occurrences of {\small\verb%x%} are different. \FAILURE Never fails. \EXAMPLE {\par\samepage\setseps\small \begin{verbatim} #term_to_print_tree true No_types "\x. x /\ T";; Print_node(term, [Print_node(ABS, [Print_node(VAR, [Print_node(x, [])]); Print_node(COMB, [Print_node(COMB, [Print_node(CONST, [Print_node(/\, [])]); Print_node(VAR, [Print_node(x, [])])]); Print_node(CONST, [Print_node(T, [])])])])]) : print_tree \end{verbatim} } \SEEALSO type_to_print_tree, thm_to_print_tree, pp_convert_term. \ENDDOC \DOC{then\_try} {\small \begin{verbatim} $then_try : (print_rule_function -> print_rule_function -> print_rule_function) \end{verbatim} }\egroup \SYNOPSIS Function for composing print-rule functions. \DESCRIBE {\small\verb%then_try%} is an infix function which forms the composite of two print-rule functions, say {\small\verb%prf1%} and {\small\verb%prf2%}. The result is a new print-rule function which, when given a tree to match, first tries the rules of {\small\verb%prf1%}; if none of these match, it then tries the rules of {\small\verb%prf2%}. \FAILURE Cannot fail when given two print-rule functions as arguments. However, the resulting function may fail when used, with this depending on the failure properties of the two argument functions. \SEEALSO hol_type_rules_fun, hol_term_rules_fun, hol_thm_rules_fun, hol_rules_fun, raw_tree_rules_fun, pretty_print, pp, pp_write. \ENDDOC \DOC{thm\_to\_print\_tree} {\small \begin{verbatim} thm_to_print_tree : (bool -> bool -> type_selection -> thm -> print_tree) \end{verbatim} }\egroup \SYNOPSIS Function for converting a HOL theorem into a print-tree. \DESCRIBE The first argument to {\small\verb%thm_to_print_tree%} determines whether or not the hypotheses (assumptions) of the theorem are included in the print-tree in full. The second argument to {\small\verb%thm_to_print_tree%} is a flag. If the flag is {\small\verb%true%}, the function converts instances of the HOL constant {\small\verb%UNCURRY%} in the theorem into an appropriate use of ordered pairs in the print-tree. If the flag is {\small\verb%false%}, {\small\verb%UNCURRY%} is treated in the same way as any other HOL constant. The conversion is necessary because the representation of tuples of bound variables in a HOL term is so unlike the syntax of the tuples that the pretty-printer cannot handle them. So, normally, the flag should be set to {\small\verb%true%}. The third argument to {\small\verb%thm_to_print_tree%} controls the amount of type information included in the print-tree of the theorem. If {\small\verb%No_types%} is given as the argument, then the print-tree will contain no type information. If {\small\verb%All_types%} is given as the argument, the tree will contain type information for every variable and constant. Use of {\small\verb%Useful_types%} instructs {\small\verb%thm_to_print_tree%} to attach type information to the bound variables of abstractions, and to one occurrence of every free variable. Type information is only included for constants if the constant is a function and it is not fully applied. So, the equals sign in {\small\verb%"1 = 2"%} would not be adorned with type information, but in {\small\verb%"$= 1"%} it would be. Finally, using {\small\verb%Hidden_types%} as the third argument to {\small\verb%thm_to_print_tree%} causes type information to be attached only to variables which, although free, without type information appear to be bound. An example of such a variable is {\small\verb%"x:num"%} in the term: {\par\samepage\setseps\small \begin{verbatim} "\(x:bool). (x:num)" \end{verbatim} } \noindent Without types, this term appears as {\small\verb%"\x. x"%}. However, the two occurrences of {\small\verb%x%} are different. \FAILURE Never fails. \EXAMPLE {\par\samepage\setseps\small \begin{verbatim} #thm_to_print_tree false true No_types (UNDISCH (SPEC_ALL FALSITY));; Print_node(thm, [Print_node(term, [Print_node(VAR, [Print_node(t, [])])]); Print_node(dots, [Print_node(dot, [])])]) : print_tree #thm_to_print_tree true true No_types (UNDISCH (SPEC_ALL FALSITY));; Print_node(thm, [Print_node(term, [Print_node(VAR, [Print_node(t, [])])]); Print_node(hyp, [Print_node(term, [Print_node(CONST, [Print_node(F, [])])])])]) : print_tree \end{verbatim} } \SEEALSO type_to_print_tree, term_to_print_tree, pp_convert_thm, pp_convert_all_thm. \ENDDOC \DOC{type\_prec} \TYPE {\small\verb%type_prec : (string -> int)%}\egroup \SYNOPSIS Precedence table for HOL types (as a function). \DESCRIBE {\small\verb%type_prec%} is a function which given the name of a HOL type operator, returns the precedence used by the pretty-printer. The standard infix type operators should be referred to by {\small\verb%fun%}, {\small\verb%prod%} and {\small\verb%sum%}, rather than by the symbolic forms. \FAILURE Never fails. \SEEALSO min_type_prec, max_type_prec, term_prec. \ENDDOC \DOC{type\_to\_print\_tree} \TYPE {\small\verb%type_to_print_tree : (type -> print_tree)%}\egroup \SYNOPSIS Function for converting a HOL type into a print-tree. \FAILURE Never fails. \EXAMPLE {\par\samepage\setseps\small \begin{verbatim} #type_to_print_tree ":* -> bool";; Print_node(type, [Print_node(OP, [Print_node(fun, []); Print_node(VAR, [Print_node(*, [])]); Print_node(OP, [Print_node(bool, [])])])]) : print_tree \end{verbatim} } \SEEALSO term_to_print_tree, thm_to_print_tree, pp_convert_type. \ENDDOC \DOC{Useful\_types} \TYPE {\small\verb%Useful_types : type_selection%}\egroup \SYNOPSIS Value used to control the amount of type information included in the print-tree of a term. \DESCRIBE {\small\verb%Useful_types%} is a value used to instruct the term-to-print-tree conversion function to attach type information to the bound variables of abstractions, and to one occurrence of every free variable. Type information is only included for constants if the constant is a function and it is not fully applied. So, the equals sign in {\small\verb%"1 = 2"%} would not be adorned with type information, but in {\small\verb%"\$= 1"%} it would be. \SEEALSO No_types, Hidden_types, All_types, term_to_print_tree. \ENDDOC `