Language

Picrin’s core language is the R7RS scheme with some powerful extensions. Please visit http://r7rs.org/ for the information of R7RS’s design and underlying thoughts.

The REPL

At the REPL start-up time, some usuful built-in libraries listed below will be automatically imported.

• (scheme base)
• (scheme load)
• (scheme process-context)
• (scheme write)
• (scheme file)
• (scheme inexact)
• (scheme cxr)
• (scheme lazy)
• (scheme time)
• (scheme case-lambda)
• (scheme read)
• (scheme eval)

Compliance with R7RS

section	status	comments
2.2 Whitespace and comments	yes
2.3 Other notations	incomplete	#e #i #b #o #d #x
2.4 Datum labels	yes
3.1 Variables, syntactic keywords, and regions
3.2 Disjointness of types	yes
3.3 External representations
3.4 Storage model	yes
3.5 Proper tail recursion	yes	As the report specifies, apply, call/cc, and call-with-values perform tail calls
4.1.1 Variable references	yes
4.1.2 Literal expressions	yes
4.1.3 Procedure calls	yes	In picrin () is self-evaluating
4.1.4 Procedures	yes
4.1.5 Conditionals	yes	In picrin (if #f #f) returns #f
4.1.6 Assignments	yes
4.1.7 Inclusion	incomplete	include-ci
4.2.1 Conditionals	yes
4.2.2 Binding constructs	yes
4.2.3 Sequencing	yes
4.2.4 Iteration	yes
4.2.5 Delayed evaluation	yes
4.2.6 Dynamic bindings	yes
4.2.7 Exception handling	yes	guard syntax.
4.2.8 Quasiquotation	yes	can be safely nested. TODO: multiple argument for unquote
4.2.9 Case-lambda	yes
4.3.1 Bindings constructs for syntactic keywords	yes [1]
4.3.2 Pattern language	yes	syntax-rules
4.3.3 Signaling errors in macro transformers	yes
5.1 Programs	yes
5.2 Import declarations	yes
5.3.1 Top level definitions	yes
5.3.2 Internal definitions	yes
5.3.3 Multiple-value definitions	yes
5.4 Syntax definitions	yes
5.5 Recored-type definitions	yes
5.6.1 Library Syntax	yes	In picrin, libraries can be reopend and can be nested.
5.6.2 Library example	N/A
5.7 The REPL	yes
6.1 Equivalence predicates	yes
6.2.1 Numerical types	yes	picrin has only two types of internal representation of numbers: fixnum and double float. It still comforms the R7RS spec.
6.2.2 Exactness	yes
6.2.3 Implementation restrictions	yes
6.2.4 Implementation extensions	yes
6.2.5 Syntax of numerical constants	yes
6.2.6 Numerical operations	yes	denominator, numerator, and rationalize are not supported for now. Also, picrin does not provide complex library procedures.
6.2.7 Numerical input and output	yes
6.3 Booleans	yes
6.4 Pairs and lists	yes	list? is safe for using against circular list.
6.5 Symbols	yes
6.6 Characters	yes
6.7 Strings	yes
6.8 Vectors	yes
6.9 Bytevectors	yes
6.10 Control features	yes
6.11 Exceptions	yes
6.12 Environments and evaluation	yes
6.13.1 Ports	yes
6.13.2 Input	yes
6.13.3 Output	yes
6.14 System interface	yes

[1]	Picrin provides hygienic macros in addition to so-called legacy macro (define-macro), such as syntactic closure, explicit renaming macro, and implicit renaming macro.