Add declarations

src/grammar.pest

@@ -1,9 +1,10 @@
 file = { "hello world" }
 
-expr = { infix_expr | term }
+statement = { decl }
+decl      = { "let" ~ #name = ident ~ #args = (ident)* ~ "=" ~ expr }
 
+expr       =  { infix_expr | term }
 term       = _{ ident | literal | "(" ~ expr ~ ")" }
-
 infix_expr =  {
     #lhs = term ~ operator ~ #rhs = expr
 }

src/test/mod.rs

@@ -1,5 +1,6 @@
 mod infix_expressions;
 mod literals;
+mod statements;
 
 use crate::parse;
 

src/test/statements.rs

@@ -0,0 +1,19 @@
+use pest::{consumes_to, parses_to};
+
+use crate::{Rule, SnekParser};
+
+#[test]
+fn it_parses_assignments() {
+    parses_to!(parser: SnekParser, input: "let a = 1", rule: Rule::statement, tokens: [
+        statement(0, 9, [
+            decl(0, 9, [
+                ident(4, 5),
+                expr(8, 9, [
+                    literal(8, 9, [
+                        integer(8, 9)
+                    ]),
+                ])
+            ])
+        ])
+    ]);
+}