177 lines
4.5 KiB
ReStructuredText
177 lines
4.5 KiB
ReStructuredText
Libraries
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=========
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Picrin's all built-in libraries are described below.
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Scheme standard libraries
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-------------------------
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- (scheme write)
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- (scheme cxr)
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- (scheme file)
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- (scheme inexact)
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- (scheme time)
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- (scheme process-context)
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- (scheme load)
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- (scheme lazy)
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SRFI libraries
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--------------
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- (srfi 1)
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List library.
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- (srfi 8)
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``receive`` macro.
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- (srfi 26)
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Cut/cute macros.
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- (srfi 43)
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Vector library.
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- (srfi 60)
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Bitwise operations.
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- (srfi 95)
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Sorting and Marging.
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(picrin macro)
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--------------
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Utility functions and syntaces for macro definition.
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- define-macro
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- gensym
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- macroexpand expr
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Old-fashioned macro.
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- make-syntactic-closure
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- identifier?
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- identifier=?
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Syntactic closures.
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- er-macro-transformer
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- ir-macro-transformer
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Explicit renaming macro family.
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(picrin regexp)
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---------------
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- **(regexp ptrn [flags])**
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Compiles pattern string into a regexp object. A string flags may contain any of #\g, #\i, #\m.
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- **(regexp? obj)**
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Judges if obj is a regexp object or not.
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- **(regexp-match re input)**
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Returns two values: a list of match strings, and a list of match indeces.
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- **(regexp-replace re input txt)**
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- **(regexp-split re input)**
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(picrin control)
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----------------
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Delimited control operators.
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- **(reset h)**
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- **(shift k)**
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(picrin control list)
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---------------------
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Monadic list operators.
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The triple of for/in/yield enables you to write a list operation in a very easy and simple code. One of the best examples is list composition::
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(for (let ((a (in '(1 2 3)))
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(b (in '(2 3 4))))
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(yield (+ a b))))
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;=> (5 6 7 6 7 8 7 8 9)
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All monadic operations are done in *for* macro. In this example, *in* operators choose an element from the given lists, a and b are bound here, then *yielding* the sum of them. Because a and b are values moving around in the list elements, the expression (+ a b) can become every possible result. *yield* operator is a operator that gathers the possibilities into a list, so *for* macro returns a list of 3 * 3 results in total. Since expression inside *for* macro is a normal expression, you can write everything that you can write elsewhere. The code below has perfectly the same effect to above one::
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(for (yield (+ (in '(1 2 3))
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(in '(4 5 6)))))
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The second best exmaple is filtering. In the next case, we show that you can do something depending on the condition of chosen elements::
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(for (let ((x (in (iota 10))))
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(if (even? x)
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(yield x)
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(null))))
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;=> (0 2 4 6 8)
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This expression is equivalent to ``(filter even? (iota 10))`` but it is more procedual and non-magical.
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- **(for expr)**
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[Macro] Executes expr in a list monad context.
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- **(in list)**
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Choose a value from list. *in* function must only appear in *for* macro. The delimited continuation from the position of *in* function to the outside *for* macro is executed for each element in list. If list contains no values, that is ``(in '())``, the continuation is discarded.
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- **(yield value)**
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Yields value from the monad context. The result of *for* will be a list of yielded values.
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- **(null . value)**
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Returns ``()`` whatever value is given. The identity element of list composition. This operator corresponds to Haskell's fail method of Monad class.
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(picrin dictionary)
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-------------------
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Symbol to Object table. Internally it is implemented on hash-table.
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Note that dictionary is not a weak map; if you are going to make a highly memory-consuming program with dictionaries, you should know that dictionaries keep their bound objects and never let them free until you explicitly deletes bindings.
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- **(dictionary)**
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Returns a newly allocated empty dictionary. In the future, it is planned to extend this function to take optional arguments for initial key/values.
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- **(dictionary? obj)**
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Returns #t if obj is a dictionary.
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- **(dictionary-ref dict key)**
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Look up dictionary dict for a value associated with symbol key. If no object is associated with key, it will raise an error.
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- **(dictionary-set! dict key obj)**
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If there is no value already associated with key, this function newly creates a binding of key with obj. Otherwise, updates the existing binding with given obj.
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- **(dictionary-delete dict key)**
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Deletes the binding associated with key from dict. If no binding on dict is associated with key, an error will be raised.
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- **(dictionary-size dict)**
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Returns the number of registered elements in dict.
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(picrin user)
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-------------
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When you start the REPL, you are dropped into here.
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