site/contents/reference-lang.md
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----- content-type: "page" title: "lang Module" ----- {@ _defs_.md || 0 @} {#sig||'||quote#} {#alias||'||quote#} {#sig||:||define#} {#alias||:||define#} {#sig||~||delete#} {#sig||+||module#} {#sig||^||call#} {#alias||^||call#} {#sig||@||bind#} {#alias||@||bind#} {#sig||>||save-symbol#} {#sig||<||load-symbol#} {#alias||->||dequote#} {#alias||>>||prefix-dequote#} {#alias||><||infix-dequote#} {#alias||=>||apply#} {#sig||#||quote-bind#} {#alias||#||quote-bind#} {#sig||=||quote-define#} {#alias||=||quote-define#} {#op||apply||{{q}}|{{d}}||({{a0p}})|{{{a0p}}}|| > This operator can be used on a quotation or a dictionary: > > * If a quotation {{q}} is passed, it returns a new quotation obtained by evaluating each element of {{q}} in a separate stack. > * If a dictionary {{d}} (with values and keys) is passed, it returns a new dictionary obtained by evaluating each value in the dict that is a symbol in a separate stack (values that aren't symbols stay as they are).#} {#op||args||{{null}}||{{q}}|| Returns a list of all arguments passed to the current program.#} {#op||bind||{{any}} {{sl}}||{{null}}|| Binds the specified value (auto-quoted) to an existing symbol {{sl}}.#} {#op||bool||{{any}}||{{b}}|| > Converts {{any}} to a boolean value based on the following rules: > > * If {{any}} is a boolean value, no conversion is performed. > * If {{any}} is a numeric value, zero is converted to {{f}}, otherwise it is converted to {{t}}. > * If {{any}} is a quotation or a dictionary, the empty quotation or dictionary is converted to {{f}}, otherwise it is converted to {{t}}. > * If {{any}} is a string, the empty string, and `"false"` are converted to {{f}}, otherwise it is converted to {{t}}.#} {#op||call||{{d}} {{sl}}||{{a0p}}|| Calls operator {{sl}} defined in dictionary {{d}}. #} {#op||case||(({{q1}} {{q2}}){{0p}})||{{a0p}}|| > This operator takes a quotation containing _n_ different conditional branches. > > Each branch must be a quotation containing two quotations, and it is processed as follows: > > * if {{q1}} evaluates to {{t}}, then the {{q2}} is executed. > * if {{q1}} evaluates to {{f}}, then the following branch is processed (if any). > > > %sidebar% > > Example > > > > The following program prints "Smaller than 3": > > > > 2 ( > > ((> 3) ("Greater than 3" put!)) > > ((< 3) ("Smaller than 3" put!)) > > ((true) ("Exactly 3" put!)) > > ) case #} {#op||define||{{any}} {{sl}}||{{null}}|| Defines a new symbol {{sl}}, containing the specified value (auto-quoted if not already a quotation).#} {#op||defined?||{{sl}}||{{b}}|| Returns {{t}} if {{sl}} is defined, {{f}} otherwise.#} {#op||delete||{{sl}}||{{null}}|| Deletes the specified symbol {{sl}}.#} {#op||dequote||{{q}}||{{a0p}}|| > Pushes the contents of quotation {{q}} on the stack. > > Each element is pushed on the stack one by one. If any error occurs, {{q}} is restored on the stack.#} {#op||eval||{{s}}||{{a0p}}|| Parses and interprets {{s}}. #} {#op||exit||{{i}}||{{null}}|| Exits the program or shell with {{i}} as return code. #} {#op||expect||{{q1}}||{{q2}}|| > Validates the first _n_ elements of the stack against the type descriptions specified in {{q1}} (_n_ is {{q1}}'s length) and if all the elements are valid returns them wrapped in {{q2}} (in reverse order). > > %tip% > > Tips > > > > * You can specify a typed dictionary by prepending the type name with `dict:`. Example: `dict:socket` > > * You can specify two or more matching types by separating the type names with a pipe: `string|quot` > > %sidebar% > > Example > > > > Assuming that the following elements are on the stack (from top to bottom): > > > > `1 "test" 3.4` > > > > the following program evaluates to `true`: > > > > `(int string num) expect (3.4 "test" 1) ==`#} {#op||float||{{any}}||{{flt}}|| > Converts {{any}} to an integer value based on the following rules: > > * If {{any}} is {{t}}, it is converted to `1.0`. > * If {{any}} is {{f}}, it is converted to `0.0`. > * If {{any}} is a integer, it is converted to float value. > * If {{any}} is a float, no conversion is performed. > * If {{any}} is a string, it is parsed as a float value.#} {#op||foreach||{{q1}} {{q2}}||{{a0p}}|| Applies the quotation {{q2}} to each element of {{q1}}.#} {#op||format-error||{{e}}||{{s}}|| > Formats the error {{e}} as a string. > > %sidebar% > > Example > > > > The following: > > > > `{"MyError" :error "This is a test error" :message} 'error set-type format-error` > > > > produces: `"This is a test error"`#} {#op||from-json||{{s}}||{{any}}|| Converts a JSON string into {{m}} data.#} {#op||from-yaml||{{s}}||{{any}}|| > Converts a YAML string into {{m}} data. > > %note% > > Note > > > > At present, only YAML objects containing string values are supported.#} {#op||if||{{q1}} {{q2}} {{q3}}||{{a0p}}|| If {{q1}} evaluates to {{t}} then evaluates {{q2}}, otherwise evaluates {{q3}}.#} {#op||import||{{sl}}||{{null}}|| Imports the a previously-loaded module {{sl}}, defining all its symbols in the current scope. #} {#op||infix-dequote||{{q}}||{{any}}|| > Dequotes {{q}} using infix notation. > > > %note% > > No operator precedence > > > > No special operator preference is defined, symbols precedence is always left-to-right. However, you can use parentheses (quotes) to evaluate expressions before others. > > > %sidebar% > > Example > > > > The following program leaves `17` on the stack: > > (2 + (3 * 5)) infix-dequote > > > > while this program leaves `25` on the stack: > > (2 + 3 * 5) infix-dequote #} {#op||int||{{any}}||{{i}}|| > Converts {{any}} to an integer value based on the following rules: > > * If {{any}} is {{t}}, it is converted to `1`. > * If {{any}} is {{f}}, it is converted to `0`. > * If {{any}} is an integer, no conversion is performed. > * If {{any}} is a float, it is converted to an integer value by truncating its decimal part. > * If {{any}} is a string, it is parsed as an integer value.#} {#op||linrec||{{q1}} {{q2}} {{q3}} {{q4}}||{{a0p}}|| > Implements linear recursions as follows: > > 1. Evaluates {{q1}}. > * If {{q1}} evaluates to {{t}}, then it evaluates {{q2}}. > * Otherwises it executes {{q3}} and recurses using the same four quotations. > 2. Finally, it executes {{q4}}. > > > %sidebar% > > Example > > > > The following program leaves `120` on the stack, the factorial of 5: > > > > 5 (dup 0 ==) 'succ (dup pred) '* linrec #} {#op||lite?||{{null}}||{{b}}|| Returns {{t}} if min was built in _lite_ mode. #} {#op||load||{{sl}}||{{a0p}}|| Parses and interprets the specified {{m}} file, adding [.min](class:ext) if not specified. #} {#op||load-symbol||{{sl}}||{{a0p}}|| Loads the contents of symbol {{sl}} from the [.min\_symbols](class:file) file. #} {#op||loglevel||{{sl}}||{{null}}|| > Sets the current logging level to {{sl}}. {{sl}} must be one of the following strings or quoted symbols: > > * debug > * info > * notice > * warn > * error > * fatal > > > %note% > > Note > > > > The default logging level is _notice_.#} {#op||loglevel?||{{null}}||{{s}}|| Returns the current log level (debug, info, notive, warn, error or fatal). #} {#op||module||{{d}} {{sl}}||{{null}}|| Creates a new module {{sl}} based on dictionary {{d}}. #} {#op||opts||{{null}}||{{d}}|| Returns a dictionary of all options passed to the current program, with their respective values.#} {#op||parse||{{s}}||{{q}}|| Parses {{s}} and returns a quoted program {{q}}. #} {#op||prefix-dequote||{{q}}||{{any}}|| > Dequotes {{q}} using prefix notation (essentially it reverses {{q}} and dequotes it. > > > %sidebar% > > Example > > > > The following program leaves `4` on the stack: > > (* 8 4) prefix-dequote #} {#op||prompt||{{null}}||{{s}}|| > This symbol is used to configure the prompt of the min shell. By default, it is set to the following quotation: > > ("[$1]$$ " (.) => %) > > Unlike other predefined symbols, this symbol is _unsealed_, which means it can be modified.#} {#op||publish||{{sl}} {{d}}||{{null}}|| > Publishes symbol {{sl}} to the scope of {{d}}. > > > %sidebar% > > Example > > > Publish symbol [my-local-symbol](class:kwd) to [ROOT](class:kwd) scope: > > `'my-local-symbol ROOT publish` #} {#op||quote||{{any}}||({{any}})|| Wraps {{any}} in a quotation. #} {#op||quote-bind||{{any}} {{sl}}||{{null}}|| Quotes {{any}} and binds the quotation to the existing symbol {{sl}}. #} {#op||quote-define||{{any}} {{sl}}||{{null}}|| Quotes {{any}} and assigns the quotation to the symbol {{sl}}, creating it if not already defined. #} {#op||raise||{{e}}||{{null}}|| Raises the error specified via the dictionary {{e}}.#} {#op||read||{{sl}}||{{q}}|| Reads and parses the specified {{m}} file {{sl}} and returns a quoted program {{q}}. #} {#op||remove-symbol||{{sl}}||{{null}}|| Removes the symbol {{sl}} from the [.min\_symbols](class:file) file. #} {#op||ROOT||{{null}}||{{d}}|| Returns a module holding a reference to the [ROOT](class:kwd) scope. > > %tip% > > Tip > > > > This symbol is very useful in conjunction with the **with** operator. #} {#op||save-symbol||{{sl}}||{{null}}|| Saves the contents of symbol {{sl}} to the [.min\_symbols](class:file) file. #} {#op||scope||{{null}}||{{d}}|| > Returns a dictionary {{d}} holding a reference to the current scope. > > This can be useful to save a reference to a given execution scope to access later on. > > > %sidebar% > > Example > > > > The following program leaves `{(2) :two ;module}` on the stack: > > > > {} :myscope (2 :due scope @myscope) -> #} {#op||saved-symbols||{{null}}||({{s0p}})|| Returns a quotation containing all symbols saved in the [.min\_symbols](class:file) file. #} {#op||scope-sigils||{{d}}||({{s0p}})|| Returns a list of all sigils defined in dictionary {{d}}.#} {#op||scope-symbols||{{d}}||({{s0p}})|| Returns a list of all symbols defined in dictionary {{d}}.#} {#op||seal||{{sl}}||{{null}}|| Seals symbol {{sl}}, so that it cannot be re-assigned. #} {#op||set-type||{{d}} {{sl}}||{{d}}|| Sets the type for dictionary {{d}} to {{sl}}.#} {#op||sigils||{{null}}||({{s0p}})|| Returns a list of all sigils defined in the [ROOT](class:kwd) scope.#} {#op||source||{{sl}}||{{q}}|| Display the source code of symbol {{sl}} (if it has been implemented a {{m}} quotation). #} {#op||string||{{any}}||{{s}}|| Converts {{any}} to its string representation.#} {#op||symbols||{{null}}||({{s0p}})|| Returns a list of all symbols defined in the [ROOT](class:kwd) scope.#} {#op||tap||{{any}} {{q}}||{{any}}|| > Performs the following operations: > > 1. Removes {{any}} from the stack. > 2. For each quotation defined in {{q}} (which is a quotation of quotations each requiring one argument and returning one argument): > 1. Pushes {{any}} back to the stack. > 2. Dequotes the quotation and saves the result as {{any}}. > 3. Push the resulting {{any}} back on the stack. > > > %sidebar% > > Example > > > > The following program: > > > > ( > > (("a" 1) ("b" 2) ("c" 3)) ( > > (dup /a succ succ %a) > > (dup /b succ %b) > > ) tap > > > > Returns `(("a" 3) ("b" 3) ("c" 3))`.#} {#op||tap!||{{any}} {{q}}||{{any}}|| > Performs the following operations: > > 1. Removes {{any}} from the stack. > 2. For each quotation defined in {{q}} (which is a quotation of quotations each requiring one argument and returning one argument): > 1. Pushes {{any}} back to the stack. > 2. Dequotes the quotation and saves the result as {{any}}. > > > %sidebar% > > Example > > > > The following program: > > > > "" :s1 > > "test" ( > > (' "1" swap append "" join) > > (' "2" swap append "" join) > > (' "3" swap append "" join @s1 s1) > > ) tap! > > > > Sets `s1` to `"test123"`. #} {#op||times||{{q}} {{i}}||{{a0p}}|| Applies the quotation {{q}} {{i}} times.#} {#op||to-json||{{any}}||{{s}}|| Converts {{any}} into a JSON string.#} {#op||to-yaml||{{any}}||{{s}}|| > Converts {{any}} into a YAML string. > > %note% > > Note > > > > At present, only {{m}} dictionaries containing string values are supported.#} {#op||try||({{q1}} {{q}}{{2}}{{01}} {{q}}{{3}}{{01}})||{{a0p}}|| > Evaluates a quotation as a try/catch/finally block. > > The must contain the following elements: > > 1. A quotation {{q1}} containing the code to be evaluated (_try_ block). > 1. _(optional)_ A quotation {{q2}} containing the code to execute in case of error (_catch_ block). > 1. _(optional)_ A quotation {{q3}} containing the code to execute after the code has been evaluated, whether an error occurred or not (_finally_ block). > > > %sidebar% > > Example > > > > The following program executed on an empty stack prints the message "Insufficient items on the stack" and pushes 0 on the stack: > > > > ( > > (pop) > > (format-error puts) > > (0) > > ) try #} {#op||unless||{{q1}} {{q2}}||{{a0p}}|| If {{1}} evaluates to {{f}} then evaluates {{2}}.#} {#op||unseal||{{sl}}||{{null}}|| Unseals symbol {{sl}}, so that it can be re-assigned. #} {#op||version||{{null}}||{{s}}|| Returns the current min version number. #} {#op||when||{{q1}} {{q2}}||{{a0p}}|| If {{q1}} evaluates to {{t}} then evaluates {{q2}}.#} {#op||while||{{q1}} {{q2}}||{{a0p}}|| > Executes {{q2}} while {{q1}} evaluates to {{t}}. > > > %sidebar% > > Example > > > > The following program prints all natural numbers from 0 to 10: > > > > 0 :count > > (count 10 <=) > > (count puts succ @count) while #} {#op||with||{{q1}} {{q2}}||{{a0p}}|| Pushes each item of {{q1}} on the stack using the scope of {{q2}} as scope. > > %sidebar% > > Example > > > > This operator is useful to define symbols on the [ROOT](class:kwd) scope or another scope. For example min's prelude includes the following code used to import certain modules only if min was not compiled in lite mode: > > > > 'lite? ( > > ( > > 'crypto import > > 'math import > > 'net import > > 'http import > > ) ROOT with > > ) unless #} |