Add some type declarations

src/grammar.pest

@@ -2,9 +2,15 @@ file = { "hello world" }
 
 block      =  { "{" ~ MLF ~ block_line ~ MLF ~ "}" }
 block_line = _{ expr | (statement ~ MLF)* }
-statement  =  { (decl | expr) ~ TERMINATE }
+statement  =  { (decl | type_decl | expr) ~ TERMINATE }
 decl       =  { "let" ~ #name = ident ~ #args = (ident)* ~ "=" ~ expr }
 
+type_decl  =  { "type" ~ #name = type_ident ~ "=" ~ type_expr }
+type_expr  =  { tuple | type_ident }
+tuple      =  { "#(" ~ type_expr* ~ ")" }
+type_ident = ${ #name = ident ~ #args = type_args? }
+type_args  =  { "<" ~ type_ident* ~ ">" }
+
 expr       =  { infix_expr | call_expr | term }
 term       = _{ ident | literal | "(" ~ MLF ~ expr ~ MLF ~ ")" | block }
 call_expr  =  {

src/test/expressions.rs

@@ -130,4 +130,27 @@ fn it_parses_calls() {
             ])
         ])
     ]);
+    parses_to!(parser: SnekParser, input: "print {1 + 1} a", rule: Rule::expr, tokens: [
+        expr(0, 15, [
+            call_expr(0, 15, [
+                ident(0, 5),
+                block(6, 13, [
+                    expr(7, 12, [
+                        infix_expr(7, 12, [
+                            literal(7, 8, [
+                                integer(7, 8)
+                            ]),
+                            operator(9, 10),
+                            expr(11, 12, [
+                                literal(11, 12, [
+                                    integer(11, 12)
+                                ]),
+                            ])
+                        ])
+                    ])
+                ]),
+                ident(14, 15)
+            ])
+        ])
+    ]);
 }

src/test/mod.rs

@@ -1,6 +1,7 @@
 mod expressions;
 mod literals;
 mod statements;
+mod types;
 
 use crate::parse;
 

src/test/types.rs

@@ -0,0 +1,79 @@
+use pest::{consumes_to, parses_to};
+
+use crate::{Rule, SnekParser};
+
+#[test]
+fn it_parses_aliases() {
+    parses_to!(parser: SnekParser, input: "type MyNum = Num", rule: Rule::statement, tokens: [
+        statement(0, 16, [
+            type_decl(0, 16, [
+                type_ident(5, 10, [
+                    ident(5, 10)
+                ]),
+                type_expr(13, 16, [
+                    type_ident(13, 16, [
+                        ident(13, 16)
+                    ])
+                ])
+            ]),
+            EOI(16, 16)
+        ])
+    ]);
+}
+
+#[test]
+fn it_parses_tuples() {
+    parses_to!(parser: SnekParser, input: "type MyTuple = #(Str Int)", rule: Rule::statement, tokens: [
+        statement(0, 25, [
+            type_decl(0, 25, [
+                type_ident(5, 12, [
+                    ident(5, 12)
+                ]),
+                type_expr(15, 25, [
+                    tuple(15, 25, [
+                        type_expr(17, 20, [
+                            type_ident(17, 20, [
+                                ident(17, 20)
+                            ])
+                        ]),
+                        type_expr(21, 24, [
+                            type_ident(21, 24, [
+                                ident(21, 24)
+                            ])
+                        ]),
+                    ])
+                ])
+            ]),
+            EOI(25, 25)
+        ])
+    ]);
+}
+
+#[test]
+fn it_parses_generics() {
+    parses_to!(parser: SnekParser, input: "type MyNum<a> = Num<a>", rule: Rule::statement, tokens: [
+        statement(0, 22, [
+            type_decl(0, 22, [
+                type_ident(5, 13, [
+                    ident(5, 10),
+                    type_args(10, 13, [
+                        type_ident(11, 12, [
+                            ident(11, 12)
+                        ])
+                    ])
+                ]),
+                type_expr(16, 22, [
+                    type_ident(16, 22, [
+                        ident(16, 19),
+                        type_args(19, 22, [
+                            type_ident(20, 21, [
+                                ident(20, 21)
+                            ])
+                        ])
+                    ])
+                ])
+            ]),
+            EOI(22, 22)
+        ])
+    ]);
+}