Punkt

Punkt (pronounced pυηkt) means dot, point or period in German.

Tokens

Token type	REGEX
keyword	alloc bool char const dealloc else false float for function if int main print println rat return sizeof string true var void while
identifier	[ _ a-z A-Z ] [ _ a-z A-Z 0-9 ]*
booleanLiteral	true false
characterLiteral	' ASCII character '
integerLiteral	[ 0-9 ]+
floatLiteral	[ 0-9 ]* . [ 0-9 ]+ ((e | E ) (+ | -)? [ 0-9 ]+)?
stringLiteral	"[ ^ " \n ]*"
Arithmetic operators	+ - * /
Other operators	= % // ! && || sizeof alloc []
Comparison operators	== != > >= < <=
Punctuators	{ } ( ) . , < > ->

Grammar

This is a description of Punkt grammar, simplified slightly for better readability. The grammar that the Punkt parser actually implements is entirely unambiguous.

$$\begin{aligned} Program \rightarrow & \enspace FunctionDefinition^* \enspace \texttt{main} \enspace CodeBlock \\[16pt] FunctionDefinition \rightarrow & \enspace \texttt{function} \enspace identifier \enspace Lambda \\[16pt] Lambda \rightarrow & \enspace \texttt{<} \enspace ParameterList^? \enspace \texttt{>} \enspace \texttt{->} \enspace Type \enspace CodeBlock \\[16pt] ParameterList \rightarrow & \enspace Type \enspace identifier \enspace (\texttt{,} \enspace Type \enspace identifier)^* \\[16pt] CodeBlock \rightarrow & \enspace \texttt{\{} \enspace Statement^* \enspace \texttt{\}} \\[16pt] Statement \rightarrow & \enspace CodeBlock \\\ | & \enspace DeclarationStatement \\\ | & \enspace ExpressionStatement \\\ | & \enspace IfStatement \\\ | & \enspace WhileStatement \\\ | & \enspace ForStatement \\\ | & \enspace ReturnStatement \\\ | & \enspace PrintStatement \\[16pt] DeclarationStatement \rightarrow & \enspace \texttt{const} \enspace identifier \enspace \texttt{=} \enspace Expression \enspace \texttt{.} \\\ | & \enspace \texttt{var} \enspace identifier \enspace \texttt{=} \enspace Expression \enspace \texttt{.} \\[16pt] ExpressionStatement \rightarrow & \enspace Expression \enspace \texttt{.} \\[16pt] IfStatement \rightarrow & \enspace \texttt{if} \enspace Expression \enspace (Statement \enspace | \enspace CodeBlock) \enspace (\texttt{else} \enspace (Statement \enspace | \enspace CodeBlock))^? \\[16pt] WhileStatement \rightarrow & \enspace \texttt{while} \enspace Expression \enspace (Statement \enspace | \enspace CodeBlock) \\[16pt] ForStatement \rightarrow & \enspace \texttt{for} \enspace (DeclarationStatement \enspace | \enspace Expression) \enspace \texttt{,} \enspace Expression \enspace \texttt{,} \enspace Expression \enspace CodeBlock \\[16pt] ReturnStatement \rightarrow & \enspace \texttt{return} \enspace Expression^? \enspace \texttt{.} \\[16pt] PrintStatement \rightarrow & \enspace \texttt{print} \enspace PrintExpressionList \enspace \texttt{.} \\\ | & \enspace \texttt{println} \enspace PrintExpressionList \enspace \texttt{.} \\[16pt] PrintExpressionList \rightarrow & \enspace Expression \enspace (\texttt{,} \enspace Expression)^* \\[16pt] Type \rightarrow & \enspace BaseType \\\ | & \enspace ArrayType \\\ | & \enspace LambdaType \\[16pt] BaseType \rightarrow & \enspace \texttt{void} \\\ | & \enspace \texttt{bool} \\\ | & \enspace \texttt{char} \\\ | & \enspace \texttt{int} \\\ | & \enspace \texttt{float} \\\ | & \enspace \texttt{rat} \\\ | & \enspace \texttt{string} \\[16pt] ArrayType \rightarrow & \enspace \texttt{[} \enspace Type \enspace \texttt{]} \\[16pt] LambdaType \rightarrow & \enspace \texttt{<} \enspace TypeList^? \enspace \texttt{>} \enspace \texttt{->} \enspace Type \\[16pt] TypeList \rightarrow & \enspace Type \enspace (\texttt{,} \enspace Type)^* \end{aligned}$$

Notes

• Comments start with # and continue until either the next # or the end of the line.
• Maximum identifier length is 32 characters.
• Non-void functions with no return statement cause a runtime error.
• Declaration statements that are part of a for-loop should not end with a terminator (.).