Syntax Outline

The basic unit of a Toyl program will be an expression, which may be a constant value, lambda expression, or else involve function calls and operators.  The full description of expression syntax covers almost everything else I currently envision in Toyl:

expression ::= { reference | constant | evaluable | lambda }

---

  reference ::= identifier

---

  evaluable ::= { function-call | operator-expression } [where-phrase]

---

    function-call ::= function-name "(" parameters ")"

---

      function-name ::= identifier

---

      parameters ::= expression ["," parameters]

---

    operator-expression ::= { unary-operation | binary-operation | trinary-operation }

---

      unary-operation ::= operator expression

---

      binary-operation ::= expression operator expression

---

      ternary-operation ::= expression operator expression operator expression

---

    where-phrase ::= "where" "{" declarations "}"

---

      declarations ::= declaration [";" declarations]

---

        declaration ::= identifier "=" expression

---

  lambda ::= return-type function-type "(" parameter-declarations ")" "{" expression "}"

---

    function-type ::= "function" | "process"

---

    parameter-declarations ::= parameter-declaration ["," parameter-declarations]

---

      parameter-declaration ::= type identifier
Fig. 9.1: Expression syntax

Identifiers may be organized in namespaces, which (like the where-phrase above) are just collections of identifiers:

namespace ::= "namespace" "{" declarations "}"
Fig. 9.2: Namespace syntax

This looks like a good start.  In the next post, I'll try to walk through the process of translating Toyl expressions into the underlying object structures and see where my ideas break.