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


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.