Grammar

Phrase structure grammar

<program> ::= <exp>

<exp> ::= <var_exp>
        | <fn_exp>
        | <app_exp>
        | <intlit_exp>
        | <papp_exp>

<fn_exp> ::= fn '(' <var_exp>* ')' => <exp>

<app_exp> ::= '(' <exp> <exp>* ')' 

<papp_exp> ::= <prim_op> '(' <args> ')' 

<args> ::= ( <exp>  ( ',' <exp> )*  )?

Lexical grammar

<var_exp> ::= <LETTER> (<LETTER>|<DIGIT>|_)*

<intlit_exp> ::=  <DIGIT>+

<DIGIT> ::= 0 | 1 | 2 | ... | 8 | 9

<LETTER> ::= a | b | ... | z | A | B | ... | Z

<prim_op> ::=  + | * | add1

Sample programs

The interpreter uses the following startup environment:
{ x: 5, y: 6 }

Sample 1:	Integer literal
Sample 2:	Variable
Sample 3:	Primitive applications
Sample 4:	Closure (constant function)
Sample 5:	Closure (ident. function)
Sample 6:	Closure (free variable)
Sample 7:	Apply constant function
Sample 8:	Apply ident. function
Sample 9:	Apply function with free var.
Sample 10:	Apply the square function
Sample 11:	Higher-order fn: Apply twice
Sample 12:	Higher-order fn: Compose

Interpreter Version 0.01

Enter the program you want to interpret below:

Output of the interpreter:

SLang 1

Grammar

Sample programs

Interpreter Version 0.01