Revised(5) Report on the Algorithmic Language Scheme

7.1.3 Expressions

<expression> ---> <variable> | <literal> | <procedure call>
                | <lambda expression> | <conditional> | <assignment>
                | <derived expression> | <macro use> | <macro block>

<literal> ---> <quotation> | <self-evaluating>

<self-evaluating> ---> <boolean> | <number> | <character> | <string>

<quotation> ---> '<datum> | (quote <datum>)

<procedure call> ---> (<operator> <operand>*)

<operator> ---> <expression>

<operand> ---> <expression>

<lambda expression> ---> (lambda <formals> <body>)

<formals> ---> (<variable>*) | <variable> | (<variable>+ . <variable>)

<body> ---> <definition>* <sequence>

<sequence> ---> <command>* <expression>

<command> ---> <expression>

<conditional> ---> (if <test> <consequent> <alternate>)

<test> ---> <expression>

<consequent> ---> <expression>

<alternate> ---> <expression> | <empty>

<assignment> ---> (set! <variable> <expression>)

<derived expression> --->
       (cond <cond clause>+)
     | (cond <cond clause>* (else <sequence>))
     | (case <expression>
         <case clause>+)
     | (case <expression>
         <case clause>*
         (else <sequence>))
     | (and <test>*)
     | (or <test>*)
     | (let (<binding spec>*) <body>)
     | (let <variable> (<binding spec>*) <body>)
     | (let* (<binding spec>*) <body>)
     | (letrec (<binding spec>*) <body>)
     | (begin <sequence>)
     | (do (<iteration spec>*)
           (<test> <do result>)
         <command>*)
     | (delay <expression>)
     | <quasiquotation>

<cond clause> ---> (<test> <sequence>)
                 | (<test>)
                 | (<test> => <recipient>)

<recipient> ---> <expression>

<case clause> ---> ((<datum>*) <sequence>)

<binding spec> ---> (<variable> <expression>)

<iteration spec> ---> (<variable> <init> <step>) | (<variable> <init>)

<init> ---> <expression>

<step> ---> <expression>

<do result> ---> <sequence> | <empty>

<macro use> ---> (<keyword> <datum>*)

<keyword> ---> <identifier>

<macro block> ---> (let-syntax (<syntax spec>*) <body>)
                 | (letrec-syntax (<syntax spec>*) <body>)

<syntax spec> ---> (<keyword> <transformer spec>)