Janet 1.27.0-01aab66 Documentation
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Top Level Bindings
All of the core functions, macros, and bindings that are not part of any module.
Index
% %= * *= *args* *current-file* *debug* *defdyn-prefix* *doc-color* *doc-width* *err* *err-color* *executable* *exit* *exit-value* *ffi-context* *lint-error* *lint-levels* *lint-warn* *macro-form* *macro-lints* *out* *peg-grammar* *pretty-format* *profilepath* *redef* *syspath* + ++ += - -- -= -> ->> -?> -?>> / /= < <= = > >= abstract? accumulate accumulate2 all all-bindings all-dynamics and any? apply array array? as-> as-macro as?-> asm assert bad-compile bad-parse band blshift bnot boolean? bor brshift brushift buffer buffer? bxor bytes? cancel case cfunction? chr cli-main cmp comment comp compare compare< compare<= compare= compare> compare>= compif compile complement comptime compwhen cond coro count curenv debug debugger debugger-env debugger-on-status dec deep-not= deep= def- default default-peg-grammar defdyn defer defglobal defmacro defmacro- defn defn- delay describe dictionary? disasm distinct doc doc* doc-format doc-of dofile drop drop-until drop-while dyn each eachk eachp edefer eflush empty? env-lookup eprin eprinf eprint eprintf error errorf eval eval-string even? every? extreme false? fiber-fn fiber? filter find find-index first flatten flatten-into flush flycheck for forever forv freeze frequencies from-pairs function? gccollect gcinterval gcsetinterval generate gensym get get-in getline getproto group-by hash idempotent? identity if-let if-not if-with import import* in inc index-of indexed? int? interleave interpose invert juxt juxt* keep keys keyword keyword? kvs label last length let load-image load-image-dict loop macex macex1 maclintf make-env make-image make-image-dict map mapcat marshal match max max-of mean memcmp merge merge-into merge-module min min-of mod nan? nat? native neg? next nil? not not= number? odd? one? or pairs parse parse-all partial partition partition-by pos? postwalk pp prewalk prin prinf print printf product prompt propagate protect put put-in quit range reduce reduce2 repeat repl require resume return reverse reverse! root-env run-context sandbox scan-number seq setdyn short-fn signal slice slurp some sort sort-by sorted sorted-by spit stderr stdin stdout string string? struct struct? sum symbol symbol? table table? tabseq take take-until take-while toggle trace tracev true? truthy? try tuple tuple? type unless unmarshal untrace update update-in use values var- varfn varglobal walk warn-compile when when-let when-with with with-dyns with-syms with-vars xprin xprinf xprint xprintf yield zero? zipcoll
Returns the remainder of dividend / divisor.
(% 10 3) # -> 1
(% -10 3) # -> -1
(% 10 -3) # -> 1
(% -10 -3) # -> -1
(% 1.4 1) # -> 0.4
(% -1.4 1) # -> -0.4
(% 1.4 1) # -> 0.4
(% -1.4 1) # -> -0.4
(% -1.4 0) # -> -nan
(% -1.4 0) # -> -nan
Community Examples / Shorthand for (set x (% x n)).
(var x 10) # -> 10
(%= x 3) # -> 1
x # -> 1
Community Examples / sourceReturns the product of all elements in xs. If xs is empty, returns 1.
(*) # -> 1
(* 10) # -> 10
(* 10 20) # -> 200
(* 1 2 3 4 5 6 7) #-> 5040
# Can take product of array with splice, but 'product' is better
(* ;(range 1 20)) #-> 1.21645e+17
(product (range 1 20)) #-> 1.21645e+17
Community Examples / Shorthand for (set x (\* x n)).
(var x 100) # -> 100
x # -> 100
(*= x 10) # -> 1000
x # -> 1000
Community Examples / sourceDynamic bindings that will contain command line arguments at program start.Community Examples / source
Bound to the name of the currently compiling file.Community Examples / source
Enables a built in debugger on errors and other useful features for debugging in a repl.Community Examples / source
Optional namespace prefix to add to keywords declared with `defdyn`. Use this to prevent keyword collisions between dynamic bindings.Community Examples / source
Whether or not to colorize documentation printed with `doc-format`.Community Examples / source
Width in columns to print documentation printed with `doc-format`.Community Examples / source
Whether or not to turn on error coloring in stacktraces and other error messages.Community Examples / source
Name of the interpreter executable used to execute this program. Corresponds to `argv[0]` in the call to `int main(int argc, char **argv);`.Community Examples / source
When set, will cause the current context to complete. Can be set to exit from repl (or file), for example.Community Examples / source
Set the return value from `run-context` upon an exit. By default, `run-context` will return nil.Community Examples / source
Current native library for ffi/bind and other settingsCommunity Examples / source
The current lint error level. The error level is the lint level at which compilation will exit with an error and not continue.Community Examples / source
A table of keyword alias to numbers denoting a lint level. Can be used to provided custom aliases for numeric lint levels.Community Examples / source
The current lint warning level. The warning level is the lint level at which and error will be printed but compilation will continue as normal.Community Examples / source
Inside a macro, is bound to the source form that invoked the macroCommunity Examples / source
Bound to an array of lint messages that will be reported by the compiler inside a macro. To indicate an error or warning, a macro author should use `maclintf`.Community Examples / source
The implicit base grammar used when compiling PEGs. Any undefined keywords found when compiling a peg will use lookup in this table (if defined).Community Examples / source
Path to profile file loaded when starting up the repl.Community Examples / source
When set, allow dynamically rebinding top level defs. Will slow generated code and is intended to be used for development.Community Examples / source
Returns the sum of all xs. xs must be integers or real numbers only. If xs is empty, return 0.
(+) # -> 0
(+ 10) # -> 10
(+ 1 2) # -> 3
(+ 1.4 -4.5) # -> -3.1
(+ 1 2 3 4 5 6 7 8 9 10) # -> 55
# Splice can be used to sum arrays, but 'sum' is better
(+ ;(range 101)) # -> 5050
(sum (range 101)) # -> 5050
# Janet can add types that support the :+ or :r+ method
(+ (int/s64 "10") 10) # -> <core/s64 20>
# Bad types give errors
(+ nil 10) # -> error: could not find method :+ for nil, or :r+ for 10
Community Examples / Increments the var x by n.
(var x 100) # -> 100
x # -> 100
(+= x 10) # -> 110
x # -> 110
Community Examples / sourceReturns the difference of xs. If xs is empty, returns 0. If xs has one element, returns the negative value of that element. Otherwise, returns the first element in xs minus the sum of the rest of the elements.
(-) # -> 0
(- 10) # -> -10
(- 1 2) # -> -1
(+ 1.4 -4.5) # -> 5.9
# Equivalent to (- first (+ ;rest))
(- 1 2 3 4 5 6 7 8 9 10) # -> -53
# Janet can subtract types that support the :- or :r- method
(- (int/s64 "10") 10) # -> <core/s64 0>
Community Examples / Decrements the var x by n.
(var x 10) # -> 10
(-= x 20) # -> -10
x # -> -10
Community Examples / sourceThreading macro. Inserts x as the second value in the first form in `forms`, and inserts the modified first form into the second form in the same manner, and so on. Useful for expressing pipelines of data.Community Examples / source
Threading macro. Inserts x as the last value in the first form in `forms`, and inserts the modified first form into the second form in the same manner, and so on. Useful for expressing pipelines of data.Community Examples / source
Short circuit threading macro. Inserts x as the second value in the first form in `forms`, and inserts the modified first form into the second form in the same manner, and so on. The pipeline will return nil if an intermediate value is nil. Useful for expressing pipelines of data.Community Examples / source
Short circuit threading macro. Inserts x as the last value in the first form in `forms`, and inserts the modified first form into the second form in the same manner, and so on. The pipeline will return nil if an intermediate value is nil. Useful for expressing pipelines of data.Community Examples / source
(/ & xs) Returns the quotient of xs. If xs is empty, returns 1. If xs has one value x, returns the reciprocal of x. Otherwise return the first value of xs repeatedly divided by the remaining values.Community Examples /
Similar to `reduce`, but accumulates intermediate values into an array. The last element in the array is what would be the return value from `reduce`. The `init` value is not added to the array (the return value will have the same number of elements as `ind`). Returns a new array.Community Examples / source
The 2-argument version of `accumulate` that does not take an initialization value. The first value in `ind` will be added to the array as is, so the length of the return value will be `(length ind)`.Community Examples / source
Returns true if `(pred item)` returns a truthy value for every item in `xs`. Otherwise, returns the first falsey `(pred item)` result encountered. Returns true if `xs` is empty.Community Examples / source
Get all symbols available in an environment. Defaults to the current fiber's environment. If `local` is truthy, will not show inherited bindings (from prototype tables).Community Examples / source
Get all dynamic bindings in an environment. Defaults to the current fiber's environment. If `local` is truthy, will not show inherited bindings (from prototype tables).Community Examples / source
Evaluates to the last argument if all preceding elements are truthy, otherwise evaluates to the first falsey argument.Community Examples / source
Returns the first truthy value in `ind`, otherwise nil.Community Examples / source
Applies a function to a variable number of arguments. Each element in args is used as an argument to f, except the last element in args, which is expected to be an array-like. Each element in this last argument is then also pushed as an argument to f. For example: (apply + 1000 (range 10)) sums the first 10 integers and 1000.
(apply + (range 10)) # -> 45
(apply + []) # -> 0
(apply + 1 2 3 4 5 6 7 [8 9 10]) # -> 55
(apply + 1 2 3 4 5 6 7 8 9 10) # -> error: expected array|tuple, got number
# Can also be used to call macros like functions.
# Will return the macro expanded code of the original macro.
(apply for 'x 0 10 ['(print x)])
# -> (do (var _000000 0) (def _000001 10) (while ...
Community Examples / Create a new array that contains items. Returns the new array.Community Examples / source
Thread forms together, replacing `as` in `forms` with the value of the previous form. The first form is the value x. Returns the last value.Community Examples / source
Use a function or macro literal `f` as a macro. This lets any function be used as a macro. Inside a quasiquote, the idiom `(as-macro ,my-custom-macro arg1 arg2...)` can be used to avoid unwanted variable capture of `my-custom-macro`.Community Examples / source
Thread forms together, replacing `as` in `forms` with the value of the previous form. The first form is the value x. If any intermediate values are falsey, return nil; otherwise, returns the last value.Community Examples / source
Returns a new function that is the compiled result of the assembly. The syntax for the assembly can be found on the Janet website, and should correspond to the return value of disasm. Will throw an error on invalid assembly.Community Examples / source
Throw an error if x is not truthy. Will not evaluate `err` if x is truthy.Community Examples / source
Default handler for a compile error.Community Examples / source
Returns the bit-wise and of all values in xs. Each x in xs must be an integer.Community Examples /
Returns the value of x bit shifted left by the sum of all values in shifts. x and each element in shift must be an integer.Community Examples /
Returns the bit-wise or of all values in xs. Each x in xs must be an integer.Community Examples /
Returns the value of x bit shifted right by the sum of all values in shifts. x and each element in shift must be an integer.Community Examples /
Returns the value of x bit shifted right by the sum of all values in shifts. x and each element in shift must be an integer. The sign of x is not preserved, so for positive shifts the return value will always be positive.Community Examples /
Creates a buffer by concatenating the elements of `xs` together. If an element is not a byte sequence, it is converted to bytes via `describe`. Returns the new buffer.Community Examples / source
Returns the bit-wise xor of all values in xs. Each in xs must be an integer.Community Examples /
Resume a fiber but have it immediately raise an error. This lets a programmer unwind a pending fiber. Returns the same result as resume.Community Examples /
Select the body that equals the dispatch value. When `pairs` has an odd number of elements, the last is the default expression. If no match is found, returns nil.Community Examples / source
Convert a string of length 1 to its byte (ascii) value at compile time.Community Examples / source
Entrance for the Janet CLI tool. Call this function with the command line arguments as an array or tuple of strings to invoke the CLI interface.Community Examples / source
Returns -1 if x is strictly less than y, 1 if y is strictly greater than x, and 0 otherwise. To return 0, x and y must be the exact same type.Community Examples /
Takes multiple functions and returns a function that is the composition of those functions.Community Examples / source
Polymorphic compare. Returns -1, 0, 1 for x < y, x = y, x > y respectively. Differs from the primitive comparators in that it first checks to see whether either x or y implement a `compare` method which can compare x and y. If so, it uses that method. If not, it delegates to the primitive comparators.Community Examples / source
Equivalent of `<` but using polymorphic `compare` instead of primitive comparator.Community Examples / source
Equivalent of `<=` but using polymorphic `compare` instead of primitive comparator.Community Examples / source
Equivalent of `=` but using polymorphic `compare` instead of primitive comparator.Community Examples / source
Equivalent of `>` but using polymorphic `compare` instead of primitive comparator.Community Examples / source
Equivalent of `>=` but using polymorphic `compare` instead of primitive comparator.Community Examples / source
Check the condition `cnd` at compile time -- if truthy, compile `tru`, else compile `fals`.Community Examples / source
Compiles an Abstract Syntax Tree (ast) into a function. Pair the compile function with parsing functionality to implement eval. Returns a new function and does not modify ast. Returns an error struct with keys :line, :column, and :error if compilation fails. If a `lints` array is given, linting messages will be appended to the array. Each message will be a tuple of the form `(level line col message)`.Community Examples / source
Returns a function that is the complement to the argument.Community Examples / source
Evals x at compile time and returns the result. Similar to a top level unquote.Community Examples / source
Check the condition `cnd` at compile time -- if truthy, compile `(upscope ;body)`, else compile nil.Community Examples / source
Evaluates conditions sequentially until the first true condition is found, and then executes the corresponding body. If there are an odd number of forms, and no forms are matched, the last expression is executed. If there are no matches, returns nil.Community Examples / source
A wrapper for making fibers that may yield multiple values (coroutine). Same as `(fiber/new (fn [] ;body) :yi)`.Community Examples / source
Count the number of items in `ind` for which `(pred item)` is true.Community Examples / source
Get the current environment table. Same as `(fiber/getenv (fiber/current))`. If `n` is provided, gets the nth prototype of the environment table.Community Examples / source
Throws a debug signal that can be caught by a parent fiber and used to inspect the running state of the current fiber. Returns the value passed in by resume.Community Examples /
Run a repl-based debugger on a fiber. Optionally pass in a level to differentiate nested debuggers.Community Examples / source
An environment that contains dot prefixed functions for debugging.Community Examples / source
Create a function that can be passed to `run-context`'s `:on-status` argument that will drop into a debugger on errors. The debugger will only start on abnormal signals if the env table has the `:debug` dyn set to a truthy value.Community Examples / source
Like `not=`, but mutable types (arrays, tables, buffers) are considered equal if they have identical structure. Much slower than `not=`.Community Examples / source
Like `=`, but mutable types (arrays, tables, buffers) are considered equal if they have identical structure. Much slower than `=`.Community Examples / source
Define a private value that will not be exported.
# In a file module.janet
(def- private-thing :encapsulated)
(def public-thing :exposed)
# In a file main.janet
(import module)
module/private-thing # -> Unknown symbol
module/public-thing # -> :exposed
# Same as normal def with :private metadata
(def :private x private-thing :encapsulated)
Community Examples / sourceDefine a default value for an optional argument. Expands to `(def sym (if (= nil sym) val sym))`.Community Examples / source
The default grammar used for pegs. This grammar defines several common patterns that should make it easier to write more complex patterns.Community Examples / source
Define an alias for a keyword that is used as a dynamic binding. The alias is a normal, lexically scoped binding that can be used instead of a keyword to prevent typos. `defdyn` does not set dynamic bindings or otherwise replace `dyn` and `setdyn`. The alias _must_ start and end with the `*` character, usually called "earmuffs".Community Examples / source
Run `form` unconditionally after `body`, even if the body throws an error. Will also run `form` if a user signal 0-4 is received.
# Evaluates to 6 after printing "scope left!"
(defer (print "scope left!")
(+ 1 2 3))
# cleanup will always be called, even if there is a failure
(defer (cleanup)
(step-1)
(step-2)
(if (< 0.1 (math/random)) (error "failure"))
(step-3))
Community Examples / sourceDefine a private macro that will not be exported.Community Examples / source
Define a function. Equivalent to `(def name (fn name [args] ...))`.
(defn simple
[x]
(print (+ x 1)))
(simple 10) # -> 11
(defn long-body
[y]
(print y)
(print (+ y 1))
(print (+ y 2))
(+ y 3))
(defn with-docstring
"This function has a docstring"
[]
(print "hello!"))
(defn with-tags
:tag1 :tag2 :private
"Also has a docstring and a variadic argument 'more'!"
[x y z & more]
[x y z more])
(with-tags 1 2) # raises arity error
(with-tags 1 2 3) # -> (1 2 3 ())
(with-tags 1 2 3 4) # -> (1 2 3 (4))
(with-tags 1 2 3 4 5) # -> (1 2 3 (4 5))
# Tags (and other metadata) are (usually) visible in the environment.
(dyn 'with-tags) # -> @{:tag2 true :value <function with-tags> :doc "(with-tags x y z & more)\n\nAlso has a docstring..." :source-map ("repl" 4 1) :tag1 true :private true}
Community Examples / sourceDefine a private function that will not be exported.
# In a file module.janet
(defn- not-exposed-fn
[x]
(+ x x))
(not-exposed-fn 10) # -> 20
# In a file main.janet
(import module)
(module/not-exposed-fn 10) # -> Unknown symbol error
# Same as
(defn not-exposed-fn
:private
[x]
(+ x x))
Community Examples / sourceLazily evaluate a series of expressions. Returns a function that returns the result of the last expression. Will only evaluate the body once, and then memoizes the result.Community Examples / source
Returns a string that is a human-readable description of `x`. For recursive data structures, the string returned contains a pointer value from which the identity of `x` can be determined.Community Examples / source
Returns assembly that could be used to compile the given function. func must be a function, not a c function. Will throw on error on a badly typed argument. If given a field name, will only return that part of the function assembly. Possible fields are: * :arity - number of required and optional arguments. * :min-arity - minimum number of arguments function can be called with. * :max-arity - maximum number of arguments function can be called with. * :vararg - true if function can take a variable number of arguments. * :bytecode - array of parsed bytecode instructions. Each instruction is a tuple. * :source - name of source file that this function was compiled from. * :name - name of function. * :slotcount - how many virtual registers, or slots, this function uses. Corresponds to stack space used by function. * :symbolmap - all symbols and their slots. * :constants - an array of constants referenced by this function. * :sourcemap - a mapping of each bytecode instruction to a line and column in the source file. * :environments - an internal mapping of which enclosing functions are referenced for bindings. * :defs - other function definitions that this function may instantiate.Community Examples / source
Returns an array of the deduplicated values in `xs`.Community Examples / source
Shows documentation for the given symbol, or can show a list of available bindings. If `sym` is a symbol, will look for documentation for that symbol. If `sym` is a string or is not provided, will show all lexical and dynamic bindings in the current environment containing that string (all bindings will be shown if no string is given).Community Examples / source
Get the documentation for a symbol in a given environment. Function form of `doc`.Community Examples / source
Reformat a docstring to wrap a certain width. Docstrings can either be plaintext or a subset of markdown. This allows a long single line of prose or formatted text to be a well-formed docstring. Returns a buffer containing the formatted text.Community Examples / source
Searches all loaded modules in module/cache for a given binding and prints out its documentation. This does a search by value instead of by name. Returns nil.Community Examples / source
Evaluate a file, file path, or stream and return the resulting environment. :env, :expander, :source, :evaluator, :read, and :parser are passed through to the underlying `run-context` call. If `exit` is true, any top level errors will trigger a call to `(os/exit 1)` after printing the error.Community Examples / source
Drop the first n elements in an indexed or bytes type. Returns a new tuple or string instance, respectively.Community Examples / source
Same as `(drop-while (complement pred) ind)`.Community Examples / source
Given a predicate, remove elements from an indexed or bytes type that satisfy the predicate, and abort on first failure. Returns a new tuple or string, respectively.Community Examples / source
Get a dynamic binding. Returns the default value (or nil) if no binding found.Community Examples / source
Loop over each (key, value) pair in `ds`. Returns nil.Community Examples / source
Run `form` after `body` in the case that body terminates abnormally (an error or user signal 0-4). Otherwise, return last form in `body`.
# Half of the time, return "ok", the other
# half of the time, print there was an error and throw "oops".
(edefer (print "there was an error")
(if (< (math/random) 0.5)
(error "oops")
"ok"))
Community Examples / sourceFlush `(dyn :err stderr)` if it is a file, otherwise do nothing.Community Examples / source
Creates a forward lookup table for unmarshalling from an environment. To create a reverse lookup table, use the invert function to swap keys and values in the returned table.Community Examples / source
Same as `prin`, but uses `(dyn :err stderr)` instead of `(dyn :out stdout)`.Community Examples / source
Same as `print`, but uses `(dyn :err stderr)` instead of `(dyn :out stdout)`.Community Examples / source
Prints output formatted as if with `(string/format fmt ;xs)` to `(dyn :err stderr)` with a trailing newline.Community Examples / source
Throws an error e that can be caught and handled by a parent fiber.Community Examples /
A combination of `error` and `string/format`. Equivalent to `(error (string/format fmt ;args))`.Community Examples / source
Evaluates a form in the current environment. If more control over the environment is needed, use `run-context`.
(eval '(+ 1 2 3)) # -> 6
(eval '(error :oops)) # -> raises error :oops
(eval '(+ nil nil)) # -> raises error
Community Examples / sourceEvaluates a string in the current environment. If more control over the environment is needed, use `run-context`.
(eval-string "(+ 1 2 3 4)") # -> 10
(eval-string ")") # -> parse error
(eval-string "(bloop)") # -> compile error
(eval-string "(+ nil nil)") # -> runtime error
Community Examples / sourceReturns true if each value in `ind` is truthy, otherwise returns the first falsey value.Community Examples / source
Returns the most extreme value in `args` based on the function `order`. `order` should take two values and return true or false (a comparison). Returns nil if `args` is empty.Community Examples / source
A wrapper for making fibers. Same as `(fiber/new (fn [] ;body) flags)`.Community Examples / source
Given a predicate, take only elements from an array or tuple for which `(pred element)` is truthy. Returns a new array.Community Examples / source
Find the first value in an indexed collection that satisfies a predicate. Returns `dflt` if not found.Community Examples / source
Find the index of indexed type for which `pred` is true. Returns `dflt` if not found.Community Examples / source
Takes a nested array (tree) `xs` and returns the depth first traversal of it. Returns a new array.Community Examples / source
Takes a nested array (tree) `xs` and appends the depth first traversal of `xs` to array `into`. Returns `into`.Community Examples / source
Flush `(dyn :out stdout)` if it is a file, otherwise do nothing.Community Examples / source
Check a file for errors without running the file. Found errors will be printed to stderr in the usual format. Macros will still be executed, however, so arbitrary execution is possible. Other arguments are the same as `dofile`. `path` can also be a file value such as stdin. Returns nil.Community Examples / source
Do a C-style for-loop for side effects. Returns nil.Community Examples / source
Evaluate body forever in a loop, or until a break statement.Community Examples / source
Do a C-style for-loop for side effects. The iteration variable `i` can be mutated in the loop, unlike normal `for`. Returns nil.Community Examples / source
Freeze an object (make it immutable) and do a deep copy, making child values also immutable. Closures, fibers, and abstract types will not be recursively frozen, but all other types will.Community Examples / source
Get the number of occurrences of each value in an indexed data structure.Community Examples / source
Takes a sequence of pairs and creates a table from each pair. It is the inverse of `pairs` on a table. Returns a new table.Community Examples / source
Run garbage collection. You should probably not call this manually.Community Examples / source
Returns the integer number of bytes to allocate before running an iteration of garbage collection.Community Examples / source
Set an integer number of bytes to allocate before running garbage collection. Low values for interval will be slower but use less memory. High values will be faster but use more memory.Community Examples / source
Create a generator expression using the `loop` syntax. Returns a fiber that yields all values inside the loop in order. See `loop` for details.
# An infinite stream of random numbers, but doubled.
(def g (generate [_ :iterate true :repeat 2] (math/random)))
# -> <fiber 0x5562863141E0>
(resume g) # -> 0.487181
(resume g) # -> 0.487181
(resume g) # -> 0.507917
(resume g) # -> 0.507917
# ...
Community Examples / sourceReturns a new symbol that is unique across the runtime. This means it will not collide with any already created symbols during compilation, so it can be used in macros to generate automatic bindings.Community Examples / source
Get the value mapped to key in data structure ds, and return dflt or nil if not found. Similar to in, but will not throw an error if the key is invalid for the data structure unless the data structure is an abstract type. In that case, the abstract type getter may throw an error.Community Examples /
Access a value in a nested data structure. Looks into the data structure via a sequence of keys. If value is not found, and `dflt` is provided, returns `dflt`.Community Examples / source
Reads a line of input into a buffer, including the newline character, using a prompt. An optional environment table can be provided for auto-complete. Returns the modified buffer. Use this function to implement a simple interface for a terminal program.Community Examples / source
Get the prototype of a table or struct. Will return nil if `x` has no prototype.Community Examples / source
Group elements of `ind` by a function `f` and put the results into a new table. The keys of the table are the distinct return values from calling `f` on the elements of `ind`. The values of the table are arrays of all elements of `ind` for which `f` called on the element equals that corresponding key.Community Examples / source
Gets a hash for any value. The hash is an integer can be used as a cheap hash function for all values. If two values are strictly equal, then they will have the same hash value.Community Examples / source
Check if x is a value that evaluates to itself when compiled.Community Examples / source
Make multiple bindings, and if all are truthy, evaluate the `tru` form. If any are false or nil, evaluate the `fal` form. Bindings have the same syntax as the `let` macro.Community Examples / source
Shorthand for `(if (not condition) else then)`.Community Examples / source
Similar to `with`, but if binding is false or nil, evaluates the falsey path. Otherwise, evaluates the truthy path. In both cases, `ctor` is bound to binding.Community Examples / source
Import a module. First requires the module, and then merges its symbols into the current environment, prepending a given prefix as needed. (use the :as or :prefix option to set a prefix). If no prefix is provided, use the name of the module as a prefix. One can also use "`:export true`" to re-export the imported symbols. If "`:exit true`" is given as an argument, any errors encountered at the top level in the module will cause `(os/exit 1)` to be called. Dynamic bindings will NOT be imported. Use :fresh to bypass the module cache.Community Examples / source
Function form of `import`. Same parameters, but the path and other symbol parameters should be strings instead.Community Examples / source
Get value in ds at key, works on associative data structures. Arrays, tuples, tables, structs, strings, symbols, and buffers are all associative and can be used. Arrays, tuples, strings, buffers, and symbols must use integer keys that are in bounds or an error is raised. Structs and tables can take any value as a key except nil and will return nil or dflt if not found.Community Examples /
Find the first key associated with a value x in a data structure, acting like a reverse lookup. Will not look at table prototypes. Returns `dflt` if not found.Community Examples / source
Check if x can be exactly represented as a 32 bit signed two's complement integer.Community Examples / source
Returns an array of the first elements of each col, then the second elements, etc.Community Examples / source
Returns a sequence of the elements of `ind` separated by `sep`. Returns a new array.Community Examples / source
Given an associative data structure `ds`, returns a new table where the keys of `ds` are the values, and the values are the keys. If multiple keys in `ds` are mapped to the same value, only one of those values will become a key in the returned table.Community Examples / source
Macro form of `juxt*`. Same behavior but more efficient.Community Examples / source
Returns the juxtaposition of functions. In other words, `((juxt* a b c) x)` evaluates to `[(a x) (b x) (c x)]`.Community Examples / source
Given a predicate `pred`, return a new array containing the truthy results of applying `pred` to each element in the indexed collection `ind`. This is different from `filter` which returns an array of the original elements where the predicate is truthy.Community Examples / source
Creates a keyword by concatenating the elements of `xs` together. If an element is not a byte sequence, it is converted to bytes via `describe`. Returns the new keyword.Community Examples / source
Takes a table or struct and returns and array of key value pairs like `@[k v k v ...]`. Returns a new array.Community Examples / source
Set a label point that is lexically scoped. `name` should be a symbol that will be bound to the label.Community Examples / source
Returns the length or count of a data structure in constant time as an integer. For structs and tables, returns the number of key-value pairs in the data structure.Community Examples /
Create a scope and bind values to symbols. Each pair in `bindings` is assigned as if with `def`, and the body of the `let` form returns the last value.Community Examples / source
The inverse operation to `make-image`. Returns an environment.Community Examples / source
A table used in combination with `unmarshal` to unmarshal byte sequences created by `make-image`, such that `(load-image bytes)` is the same as `(unmarshal bytes load-image-dict)`.Community Examples / source
A general purpose loop macro. This macro is similar to the Common Lisp loop macro, although intentionally much smaller in scope. The head of the loop should be a tuple that contains a sequence of either bindings or conditionals. A binding is a sequence of three values that define something to loop over. Bindings are written in the format: binding :verb object/expression where `binding` is a binding as passed to def, `:verb` is one of a set of keywords, and `object` is any expression. Each subsequent binding creates a nested loop within the loop created by the previous binding. The available verbs are: * `:iterate` -- repeatedly evaluate and bind to the expression while it is truthy. * `:range` -- loop over a range. The object should be a two-element tuple with a start and end value, and an optional positive step. The range is half open, [start, end). * `:range-to` -- same as :range, but the range is inclusive [start, end]. * `:down` -- loop over a range, stepping downwards. The object should be a two-element tuple with a start and (exclusive) end value, and an optional (positive!) step size. * `:down-to` -- same as :down, but the range is inclusive [start, end]. * `:keys` -- iterate over the keys in a data structure. * `:pairs` -- iterate over the key-value pairs as tuples in a data structure. * `:in` -- iterate over the values in a data structure or fiber. `loop` also accepts conditionals to refine the looping further. Conditionals are of the form: :modifier argument where `:modifier` is one of a set of keywords, and `argument` is keyword-dependent. `:modifier` can be one of: * `:while expression` -- breaks from the current loop if `expression` is falsey. * `:until expression` -- breaks from the current loop if `expression` is truthy. * `:let bindings` -- defines bindings inside the current loop as passed to the `let` macro. * `:before form` -- evaluates a form for a side effect before the next inner loop. * `:after form` -- same as `:before`, but the side effect happens after the next inner loop. * `:repeat n` -- repeats the next inner loop `n` times. * `:when condition` -- only evaluates the current loop body when `condition` is true. The `loop` macro always evaluates to nil.
# -> prints 0123456789 (not followed by newline)
(loop [x :range [0 10]]
(prin x))
# Cartesian product (nested loops)
# -> prints 00010203101112132021222330313233
# Same as (for x 0 4 (for y 0 4 (prin x y)))
(loop [x :range [0 4]
y :range [0 4]]
(prin x y))
# -> prints bytes of "hello, world" as numbers
(loop [character :in "hello, world"]
(print character))
# -> prints 1, 2, and 3, in an unspecified order
(loop [value :in {:a 1 :b 2 :c 3}]
(print value))
# -> prints 0 to 99 inclusive
(loop [x :in (range 100)]
(print x))
# Complex body
(loop [x :in (range 10)]
(print x)
(print (inc c))
(print (+ x 2)))
# Iterate over keys
(loop [k :keys {:a 1 :b 2 :c 3}]
(print k))
# print a, b, and c in an unspecified order
(loop [index :keys [:a :b :c :d]]
(print index))
# print 0, 1, 2, and 3 in order.
(defn print-pairs
[x]
(loop [[k v] :pairs x]
(printf "[%v]=%v" k v)))
(print-pairs [:a :b :c])
# [0]=:a
# [1]=:b
# [2]=:c
(print-pairs {:a 1 :b 2 :c 3})
# [:a]=1
# [:b]=2
# [:c]=3
# Some modifiers - allow early termination and conditional execution
# of the loop
(loop [x :range [0 100] :when (even? x)]
(print x))
# prints even numbers 0, 2, 4, ..., 98
(loop [x :range [1 100] :while (pos? (% x 7))]
(print x))
# prints 1, 2, 3, 4, 5, 6
# Consume fibers as generators
(def f
(fiber/new
(fn []
(for i 0 100
(yield i)))))
(loop [x :in f]
(print x))
# print 0, 1, 2, ... 99
# Modifiers in nested loops
(loop [x :range [0 10]
:after (print)
y :range [0 x]]
(prin y " "))
# 0
# 0 1
# 0 1 2
# 0 1 2 3
# 0 1 2 3 4
# 0 1 2 3 4 5
# 0 1 2 3 4 5 6
# 0 1 2 3 4 5 6 7
# 0 1 2 3 4 5 6 7 8
Community Examples / sourceExpand macros completely. `on-binding` is an optional callback for whenever a normal symbolic binding is encountered. This allows macros to easily see all bindings used by their arguments by calling `macex` on their contents. The binding itself is also replaced by the value returned by `on-binding` within the expanded macro.Community Examples / source
Expand macros in a form, but do not recursively expand macros. See `macex` docs for info on `on-binding`.Community Examples / source
When inside a macro, call this function to add a linter warning. Takes a `fmt` argument like `string/format`, which is used to format the message.Community Examples / source
Create a new environment table. The new environment will inherit bindings from the parent environment, but new bindings will not pollute the parent environment.Community Examples / source
Create an image from an environment returned by `require`. Returns the image source as a string.Community Examples / source
A table used in combination with `marshal` to marshal code (images), such that `(make-image x)` is the same as `(marshal x make-image-dict)`.Community Examples / source
Map a function over every value in a data structure and return an array of the results.Community Examples / source
Map a function over every element in an array or tuple and use `array/concat` to concatenate the results.Community Examples / source
Marshal a value into a buffer and return the buffer. The buffer can then later be unmarshalled to reconstruct the initial value. Optionally, one can pass in a reverse lookup table to not marshal aliased values that are found in the table. Then a forward lookup table can be used to recover the original value when unmarshalling.Community Examples / source
Pattern matching. Match an expression `x` against any number of cases. Each case is a pattern to match against, followed by an expression to evaluate to if that case is matched. Legal patterns are: * symbol -- a pattern that is a symbol will match anything, binding `x`'s value to that symbol. * array or bracket tuple -- an array or bracket tuple will match only if all of its elements match the corresponding elements in `x`. Use `& rest` at the end of an array or bracketed tuple to bind all remaining values to `rest`. * table or struct -- a table or struct will match if all values match with the corresponding values in `x`. * tuple -- a tuple pattern will match if its first element matches, and the following elements are treated as predicates and are true. * `_` symbol -- the last special case is the `_` symbol, which is a wildcard that will match any value without creating a binding. While a symbol pattern will ordinarily match any value, the pattern `(@ <sym>)`, where <sym> is any symbol, will attempt to match `x` against a value already bound to `<sym>`, rather than matching and rebinding it. Any other value pattern will only match if it is equal to `x`. Quoting a pattern with `'` will also treat the value as a literal value to match against.Community Examples / source
Returns the numeric maximum of the argument sequence.Community Examples / source
Compare memory. Takes two byte sequences `a` and `b`, and return 0 if they have identical contents, a negative integer if a is less than b, and a positive integer if a is greater than b. Optionally take a length and offsets to compare slices of the bytes sequences.Community Examples / source
Merges multiple tables/structs into one new table. If a key appears in more than one collection in `colls`, then later values replace any previous ones. Returns the new table.Community Examples / source
Merges multiple tables/structs into table `tab`. If a key appears in more than one collection in `colls`, then later values replace any previous ones. Returns `tab`.Community Examples / source
Merge a module source into the `target` environment with a `prefix`, as with the `import` macro. This lets users emulate the behavior of `import` with a custom module table. If `export` is truthy, then merged functions are not marked as private. Returns the modified target environment.Community Examples / source
Returns the numeric minimum of the argument sequence.Community Examples / source
Check if x can be exactly represented as a non-negative 32 bit signed two's complement integer.Community Examples / source
Load a native module from the given path. The path must be an absolute or relative path on the file system, and is usually a .so file on Unix systems, and a .dll file on Windows. Returns an environment table that contains functions and other values from the native module.Community Examples / source
Gets the next key in a data structure. Can be used to iterate through the keys of a data structure in an unspecified order. Keys are guaranteed to be seen only once per iteration if they data structure is not mutated during iteration. If key is nil, next returns the first key. If next returns nil, there are no more keys to iterate through.Community Examples /
Evaluates to the last argument if all preceding elements are falsey, otherwise evaluates to the first truthy element.Community Examples / source
Get the key-value pairs of an associative data structure.Community Examples / source
Parse a string and return the first value. For complex parsing, such as for a repl with error handling, use the parser api.Community Examples / source
Parse a string and return all parsed values. For complex parsing, such as for a repl with error handling, use the parser api.Community Examples / source
Partition an indexed data structure `ind` into tuples of size `n`. Returns a new array.Community Examples / source
Partition elements of a sequential data structure by a representative function `f`. Partitions split when `(f x)` changes values when iterating to the next element `x` of `ind`. Returns a new array of arrays.Community Examples / source
Do a post-order traversal of a data structure and call `(f x)` on every visitation.Community Examples / source
Pretty-print to stdout or `(dyn *out*)`. The format string used is `(dyn *pretty-format* "%q")`.Community Examples / source
Similar to `postwalk`, but do pre-order traversal.Community Examples / source
Print values to the console (standard out). Value are converted to strings if they are not already. After printing all values, a newline character is printed. Use the value of `(dyn :out stdout)` to determine what to push characters to. Expects `(dyn :out stdout)` to be either a core/file or a buffer. Returns nil.Community Examples / source
Prints output formatted as if with `(string/format fmt ;xs)` to `(dyn :out stdout)` with a trailing newline.Community Examples / source
Returns the product of xs. If xs is empty, returns 1.
(product []) # -> 1
(product @[1 2 3]) # -> 6
(product [0 1 2 3]) # -> 0
(product (range 1 10)) # -> 362880
# Product over byte values [0-255] in a string
(product "hello") # -> 1.35996e+10
# Product over values in a table or struct
(sum {:a 1 :b 2 :c 4}) # -> 8
Community Examples / sourceSet up a checkpoint that can be returned to. `tag` should be a value that is used in a `return` statement, like a keyword.Community Examples / source
Propagate a signal from a fiber to the current fiber. The resulting stack trace from the current fiber will include frames from fiber. If fiber is in a state that can be resumed, resuming the current fiber will first resume fiber. This function can be used to re-raise an error without losing the original stack trace.Community Examples /
Evaluate expressions, while capturing any errors. Evaluates to a tuple of two elements. The first element is true if successful, false if an error, and the second is the return value or error.Community Examples / source
Associate a key with a value in any mutable associative data structure. Indexed data structures (arrays and buffers) only accept non-negative integer keys, and will expand if an out of bounds value is provided. In an array, extra space will be filled with nils, and in a buffer, extra space will be filled with 0 bytes. In a table, putting a key that is contained in the table prototype will hide the association defined by the prototype, but will not mutate the prototype table. Putting a value nil into a table will remove the key from the table. Returns the data structure ds.Community Examples /
Put a value into a nested data structure `ds`. Looks into `ds` via a sequence of keys. Missing data structures will be replaced with tables. Returns the modified, original data structure.Community Examples / source
Tries to exit from the current repl or run-context. Does not always exit the application. Works by setting the :exit dynamic binding to true. Passing a non-nil `value` here will cause the outer run-context to return that value.Community Examples / source
Create an array of values [start, end) with a given step. With one argument, returns a range [0, end). With two arguments, returns a range [start, end). With three, returns a range with optional step size.
(range 10) # -> @[0 1 2 3 4 6 7 8 9]
(range 5 10) # -> @[5 6 7 8 9]
(range 5 10 2) # -> @[5 7 9]
(range 5 11 2) # -> @[5 7 9]
(range 10 0 -1) # -> @[10 9 8 7 6 5 4 3 2 1]
Community Examples / sourceReduce, also know as fold-left in many languages, transforms an indexed type (array, tuple) with a function to produce a value by applying `f` to each element in order. `f` is a function of 2 arguments, `(f accum el)`, where `accum` is the initial value and `el` is the next value in the indexed type `ind`. `f` returns a value that will be used as `accum` in the next call to `f`. `reduce` returns the value of the final call to `f`.Community Examples / source
The 2-argument version of `reduce` that does not take an initialization value. Instead, the first element of the array is used for initialization.Community Examples / source
Evaluate body n times. If n is negative, body will be evaluated 0 times. Evaluates to nil.Community Examples / source
Run a repl. The first parameter is an optional function to call to get a chunk of source code that should return nil for end of file. The second parameter is a function that is called when a signal is caught. One can provide an optional environment table to run the repl in, as well as an optional parser or read function to pass to `run-context`.Community Examples / source
Require a module with the given name. Will search all of the paths in `module/paths`. Returns the new environment returned from compiling and running the file.Community Examples / source
Resume a new or suspended fiber and optionally pass in a value to the fiber that will be returned to the last yield in the case of a pending fiber, or the argument to the dispatch function in the case of a new fiber. Returns either the return result of the fiber's dispatch function, or the value from the next yield call in fiber.Community Examples /
Reverses the order of the elements in a given array or tuple and returns a new array. If a string or buffer is provided, returns an array of its byte values, reversed.
(reverse [1 2 3]) # -> @[3 2 1]
(reverse "abcdef") # -> @[102 101 100 99 98 97]
(reverse :abc) # -> @[99 98 97]
Community Examples / sourceReverses the order of the elements in a given array or buffer and returns it mutated.Community Examples / source
The root environment used to create environments with (make-env).Community Examples /
Run a context. This evaluates expressions in an environment, and encapsulates the parsing, compilation, and evaluation. Returns `(in environment :exit-value environment)` when complete. `opts` is a table or struct of options. The options are as follows: * `:chunks` -- callback to read into a buffer - default is getline * `:on-parse-error` -- callback when parsing fails - default is bad-parse * `:env` -- the environment to compile against - default is the current env * `:source` -- source path for better errors (use keywords for non-paths) - default is :<anonymous> * `:on-compile-error` -- callback when compilation fails - default is bad-compile * `:on-compile-warning` -- callback for any linting error - default is warn-compile * `:evaluator` -- callback that executes thunks. Signature is (evaluator thunk source env where) * `:on-status` -- callback when a value is evaluated - default is debug/stacktrace. * `:fiber-flags` -- what flags to wrap the compilation fiber with. Default is :ia. * `:expander` -- an optional function that is called on each top level form before being compiled. * `:parser` -- provide a custom parser that implements the same interface as Janet's built-in parser. * `:read` -- optional function to get the next form, called like `(read env source)`. Overrides all parsing.Community Examples / source
Disable feature sets to prevent the interpreter from using certain system resources. Once a feature is disabled, there is no way to re-enable it. Capabilities can be: * :all - disallow all (except IO to stdout, stderr, and stdin) * :env - disallow reading and write env variables * :ffi - disallow FFI (recommended if disabling anything else) * :fs - disallow access to the file system * :fs-read - disallow read access to the file system * :fs-temp - disallow creating temporary files * :fs-write - disallow write access to the file system * :hrtime - disallow high-resolution timers * :modules - disallow load dynamic modules (natives) * :net - disallow network access * :net-connect - disallow making outbound network connections * :net-listen - disallow accepting inbound network connections * :sandbox - disallow calling this function * :subprocess - disallow running subprocessesCommunity Examples / source
Parse a number from a byte sequence and return that number, either an integer or a real. The number must be in the same format as numbers in janet source code. Will return nil on an invalid number. Optionally provide a base - if a base is provided, no radix specifier is expected at the beginning of the number.Community Examples / source
Similar to `loop`, but accumulates the loop body into an array and returns that. See `loop` for details.
(seq [x :range [0 5]] (* 2 x)) # -> @[0 2 4 6 8]
Community Examples / sourceShorthand for `fn`. Arguments are given as `$n`, where `n` is the 0-indexed argument of the function. `$` is also an alias for the first (index 0) argument. The `$&` symbol will make the anonymous function variadic if it appears in the body of the function, and can be combined with positional arguments. Example usage: (short-fn (+ $ $)) # A function that doubles its arguments. (short-fn (string $0 $1)) # accepting multiple args. |(+ $ $) # use pipe reader macro for terse function literals. |(+ $&) # variadic functionsCommunity Examples / source
Extract a sub-range of an indexed data structure or byte sequence.
(slice @[1 2 3]) # -> (1 2 3) (a new array!)
(slice @[:a :b :c] 1) # -> (:b :c)
(slice [:a :b :c :d :e] 2 4) # -> (:c :d)
(slice [:a :b :d :d :e] 2 -1) # -> (:c :d :e)
(slice [:a :b :d :d :e] 2 -2) # -> (:c :d)
(slice [:a :b :d :d :e] 2 -4) # -> ()
(slice [:a :b :d :d :e] 2 -10) # -> error: range error
(slice "abcdefg" 0 2) # -> "ab"
(slice @"abcdefg" 0 2) # -> "ab"
Community Examples / sourceRead all data from a file with name `path` and then close the file.Community Examples / source
Returns nil if all `xs` are false or nil, otherwise returns the result of the first truthy predicate, `(pred x)`.Community Examples / source
Sorts `ind` in-place, and returns it. Uses quick-sort and is not a stable sort. If a `before?` comparator function is provided, sorts elements using that, otherwise uses `<`.Community Examples / source
Sorts `ind` in-place by calling a function `f` on each element and comparing the result with `<`.Community Examples / source
Returns a new sorted array without modifying the old one. If a `before?` comparator function is provided, sorts elements using that, otherwise uses `<`.Community Examples / source
Returns a new sorted array that compares elements by invoking a function `f` on each element and comparing the result with `<`.Community Examples / source
Write `contents` to a file at `path`. Can optionally append to the file.Community Examples / source
Creates a string by concatenating the elements of `xs` together. If an element is not a byte sequence, it is converted to bytes via `describe`. Returns the new string.Community Examples / source
Create a new struct from a sequence of key value pairs. kvs is a sequence k1, v1, k2, v2, k3, v3, ... If kvs has an odd number of elements, an error will be thrown. Returns the new struct.Community Examples / source
Returns the sum of xs. If xs is empty, returns 0.
(sum []) # -> 0
(sum @[1]) # -> 1
(sum (range 100)) # -> 4950
# Sum over bytes values [0-255] in a string
(sum "hello") # -> 532
# Sum over values in a table or struct
(sum {:a 1 :b 2 :c 4}) # -> 7
Community Examples / sourceCreates a symbol by concatenating the elements of `xs` together. If an element is not a byte sequence, it is converted to bytes via `describe`. Returns the new symbol.Community Examples / source
Creates a new table from a variadic number of keys and values. kvs is a sequence k1, v1, k2, v2, k3, v3, ... If kvs has an odd number of elements, an error will be thrown. Returns the new table.Community Examples / source
Similar to `loop`, but accumulates key value pairs into a table. See `loop` for details.Community Examples / source
Take the first n elements of a fiber, indexed or bytes type. Returns a new array, tuple or string, respectively.Community Examples / source
Same as `(take-while (complement pred) ind)`.Community Examples / source
Given a predicate, take only elements from a fiber, indexed, or bytes type that satisfy the predicate, and abort on first failure. Returns a new array, tuple, or string, respectively.Community Examples / source
Set a value to its boolean inverse. Same as `(set value (not value))`.Community Examples / source
Enable tracing on a function. Returns the function.Community Examples / source
Print to stderr a value and a description of the form that produced that value. Evaluates to x.Community Examples / source
Try something and catch errors. `body` is any expression, and `catch` should be a form, the first element of which is a tuple. This tuple should contain a binding for errors and an optional binding for the fiber wrapping the body. Returns the result of `body` if no error, or the result of `catch` if an error.Community Examples / source
Creates a new tuple that contains items. Returns the new tuple.Community Examples / source
Returns the type of `x` as a keyword. `x` is one of: * :nil * :boolean * :number * :array * :tuple * :table * :struct * :string * :buffer * :symbol * :keyword * :function * :cfunction * :fiber or another keyword for an abstract type.
(type nil) # -> :nil
(type true) # -> :boolean
(type false) # -> :boolean
(type 1) # -> :number
(type :key) # -> :keyword
(type (int/s64 "100")) # -> :core/s64
Community Examples / sourceShorthand for `(when (not condition) ;body)`.Community Examples / source
Unmarshal a value from a buffer. An optional lookup table can be provided to allow for aliases to be resolved. Returns the value unmarshalled from the buffer.Community Examples / source
Disables tracing on a function. Returns the function.Community Examples / source
For a given key in data structure `ds`, replace its corresponding value with the result of calling `func` on that value. If `args` are provided, they will be passed along to `func` as well. Returns `ds`, updated.Community Examples / source
Update a value in a nested data structure `ds`. Looks into `ds` via a sequence of keys, and replaces the value found there with `f` applied to that value. Missing data structures will be replaced with tables. Returns the modified, original data structure.Community Examples / source
Similar to `import`, but imported bindings are not prefixed with a module identifier. Can also import multiple modules in one shot.Community Examples / source
Create a function that can be rebound. `varfn` has the same signature as `defn`, but defines functions in the environment as vars. If a var `name` already exists in the environment, it is rebound to the new function. Returns a function.Community Examples / source
Iterate over the values in ast and apply `f` to them. Collect the results in a data structure. If ast is not a table, struct, array, or tuple, returns form.Community Examples / source
Default handler for a compile warning.Community Examples / source
Evaluates the body when the condition is true. Otherwise returns nil.Community Examples / source
Similar to with, but if binding is false or nil, returns nil without evaluating the body. Otherwise, the same as `with`.Community Examples / source
Evaluate `body` with some resource, which will be automatically cleaned up if there is an error in `body`. `binding` is bound to the expression `ctor`, and `dtor` is a function or callable that is passed the binding. If no destructor (`dtor`) is given, will call :close on the resource.
# Print all of poetry.txt, and close the file when done,
# even when there is an error.
(with [f (file/open "poetry.txt")]
(print (:read f :all)))
Community Examples / sourceRun a block of code in a new fiber that has some dynamic bindings set. The fiber will not mask errors or signals, but the dynamic bindings will be properly unset, as dynamic bindings are fiber-local.Community Examples / source
Evaluates `body` with each symbol in `syms` bound to a generated, unique symbol.Community Examples / source
Evaluates `body` with each var in `vars` temporarily bound. Similar signature to `let`, but each binding must be a var.Community Examples / source
Print to a file or other value explicitly (no dynamic bindings). The value to print to is the first argument, and is otherwise the same as `prin`. Returns nil.Community Examples / source
Like `prinf` but prints to an explicit file or value `to`. Returns nil.Community Examples / source
Print to a file or other value explicitly (no dynamic bindings) with a trailing newline character. The value to print to is the first argument, and is otherwise the same as `print`. Returns nil.Community Examples / source
Like `printf` but prints to an explicit file or value `to`. Returns nil.Community Examples / source
Yield a value to a parent fiber. When a fiber yields, its execution is paused until another thread resumes it. The fiber will then resume, and the last yield call will return the value that was passed to resume.Community Examples /
Creates a table from two arrays/tuples. Returns a new table.Community Examples / source