diff --git a/docs/about/formalities.md b/docs/about/formalities.md
index 57871b4..246c2e2 100644
--- a/docs/about/formalities.md
+++ b/docs/about/formalities.md
@@ -8,7 +8,7 @@ s, t ::= s | t              (disjunction, a.k.a. union)
        | s => t             (implication)
        | s -> t             (arrow, a.k.a. function)
        | forall x . t       (forall, polymorphic)
-       | box t              (box, c.f. modular logic)
+       | box t              (box, c.f. modal logic)
        | a [t..]            (type operator application)
        | x                  (variable)
        | n                  (nominal)
@@ -37,23 +37,23 @@ s, γ ⊢ s, δ
 ---- [false-left]
 false, γ ⊢ δ
 
-// trace pairs: none
+// trace pairs: none?
 s, t, γ ⊢ δ
 ---- [conj-left]
 s & t, γ ⊢ δ
 
-// trace pairs: none
+// trace pairs: none?
 γ ⊢ s, t, δ
 ---- [disj-right]
 γ ⊢ s | t, δ
 
-// trace pairs: none
+// trace pairs: none?
 s, γ ⊢ δ
 t, γ ⊢ δ
 ---- [disj-left]
 s | t, γ ⊢ δ
 
-// trace pairs: none
+// trace pairs: none?
 γ ⊢ s, δ
 γ ⊢ t, δ
 ---- [conj-right]
@@ -61,12 +61,12 @@ s | t, γ ⊢ δ
 
 // XXX
 // remove s => t? always make progress
-// trace pairs: none
+// trace pairs: none?
 s => t, s, t, γ ⊢ δ
 ---- [impl-left]
 s => t, s, γ ⊢ δ
 
-// trace pairs: none
+// trace pairs: none?
 s, γ ⊢ t, δ
 ---- [impl-right]
 γ ⊢ s => t, δ
@@ -89,7 +89,7 @@ box t, γ ⊢ δ
 // to exclude typedefs like
 // type A = A
 // Or that our cycle detection excludes paths between "identical" states.
-// trace pairs: none
+// trace pairs: none?
 γ ⊢ expand(a[t..]), δ
 ----
 γ ⊢ a[t..], δ
@@ -114,6 +114,7 @@ n fresh
 ---- [forall]
 γ ⊢ δ
 
+// TODO can we choose a simpler rule instead?
 // 1 + n! premises
 // trace pairs: i ∈ [1..(n! + 1)], premise[i] -- conclusion
 c, γ*  ⊢ a_1, ..., a_n, δ*
@@ -122,9 +123,10 @@ c, γ*  ⊢ a_1, ..., a_n, δ*
 	OR
 	{ b_i | i ∈ ¬I }, γ* ⊢ d, δ*
 ---- [loads-of-fun]
-a_1 -> b_1, ..., a_n -> b_n, γ ⊢ c -> d, δ
+a_1 -> b_1, ..., a_n -> b_n, γ    ⊢    c -> d, δ
 ```
 
+
 ### context operators
 
 * box filtering
diff --git a/docs/about/progress.md b/docs/about/progress.md
index 40c97dc..9b71035 100644
--- a/docs/about/progress.md
+++ b/docs/about/progress.md
@@ -1,11 +1,9 @@
-# draft of presentation
-
-## sappho short
+# sappho short
 	- sappho types intro
 	- a quick look at msph and spho
 
 
-### The types
+## The types
 
 We take a look at the grammar for sappho types
 
@@ -15,7 +13,7 @@ s, t ::= s | t              (disjunction, a.k.a. union)
        | s => t             (implication)
        | s -> t             (arrow, a.k.a. function)
        | forall x . t       (forall, polymorphic)
-       | box t              (box, c.f. modular logic)
+       | box t              (box, c.f. modal logic)
        | a [t..]            (type operator application)
        | x                  (variable)
        | n                  (nominal)
@@ -30,7 +28,7 @@ n ∈ nominal
 a ∈ opname
 ```
 
-The type `t <: s` would be expressive sugar for `box (t => s)`
+The type `t <: s` would be syntactic sugar for `box (t => s)`
 
 ### msph and spho
 
@@ -60,7 +58,7 @@ Thoughts
 * maybe eventually add a basic term language and interpreter
 * can we use external software/libraries for proof search?
 
-## interpretation of types
+# interpretation of types
 	- example programs in `msph`
 		- unified syntax for types and bounded polymorphism
 		- example: self typing
@@ -75,7 +73,8 @@ Check formalities.md.
 	- simple rules
 	- type constructor rules
 	- recursion and cyclic proofs
-* next steps?
+
+# next steps?
 	- formals:
 		- formulate theorems
 			- if we use semantic subtyping, isn't it enough to
@@ -85,3 +84,4 @@ Check formalities.md.
 		- simple rules, should be fairly simple
 		- type constructors, straightforward hopefully
 		- recursion and cyclic proofs... `¯\_(ツ)_/¯`
+	- describe use of language with type system (interpretation of types)
diff --git a/include/msph/common.h b/include/msph/msph.h
similarity index 85%
rename from include/msph/common.h
rename to include/msph/msph.h
index eb49da4..f34980b 100644
--- a/include/msph/common.h
+++ b/include/msph/msph.h
@@ -1,5 +1,5 @@
-#ifndef _MSPH_COMMON_H
-#define _MSPH_COMMON_H
+#ifndef _MSPH_H
+#define _MSPH_H
 
 #include "msph/err.h"
 #include "spho/ctx.h"
@@ -25,4 +25,4 @@ struct msph_text_pos {
 	unsigned int	col;
 };
 
-#endif
+#endif /* ifndef _MSPH_H */
diff --git a/include/msph/token.h b/include/msph/token.h
index 21617eb..18fb7ae 100644
--- a/include/msph/token.h
+++ b/include/msph/token.h
@@ -3,7 +3,7 @@
 
 #include <sys/queue.h>
 
-#include "msph/common.h"
+#include "msph/msph.h"
 
 /*
  *
diff --git a/include/msph/tree.h b/include/msph/tree.h
index a7567ab..3fffcfc 100644
--- a/include/msph/tree.h
+++ b/include/msph/tree.h
@@ -3,7 +3,7 @@
 
 #include <sys/queue.h>
 
-#include "msph/common.h"
+#include "msph/msph.h"
 #include "msph/token.h"
 
 /* tree decorations */
diff --git a/src/msph/msph.c b/src/msph/msph.c
index 1554e61..c9d3afe 100644
--- a/src/msph/msph.c
+++ b/src/msph/msph.c
@@ -2,23 +2,11 @@
 #include <stdio.h>
 #include <unistd.h>
 
-#include "msph/err.h"
+#include "msph/msph.h"
 #include "msph/token.h"
 #include "msph/tree.h"
 #include "msph/sphophi.h"
 
-struct msph_opts {
-	int		tokenize_only;
-	int		parser;
-	const char	*in_path;
-	const char	*out_path;
-} run_opts = {
-	0,
-	MSPH_PARSE_INFIX,
-	NULL,
-	NULL
-};
-
 
 #define USAGE \
 "msph: micro sappho\n" \
@@ -35,6 +23,64 @@ print_usage(void)
 	printf("%s", USAGE);
 }
 
+struct err_info {
+	int		err;
+	const char	*msg;
+} errinfo[] = {
+	{ MSPH_ERR_SYS, "system error" },
+	{ MSPH_ERR_INVAL, "invalid argument" },
+	{ MSPH_ERR_TOOLONG, "input too long" },
+
+	{ MSPH_ERR_TOKEN_TOOLONG, "token too long" },
+	{ MSPH_ERR_TOKEN_EOF, "tokenizer reached end of file" },
+	{ MSPH_ERR_TOKEN_NOMATCH, "no matching token" },
+	{ MSPH_ERR_TOKEN_INVAL, "token invalid" },
+
+	{ MSPH_ERR_TREE_TOOLONG, "parsed data too long" },
+	{ MSPH_ERR_TREE_EOF, "parsing reached unexpected end of file" },
+	{ MSPH_ERR_TREE_NOMATCH, "parser matching failed" },
+
+	{ MSPH_ERR_TYPE_INVAL, "invalid type" },
+
+	{ MSPH_ERR_SPHOPHI, "spho error" },
+	{ -1, NULL }
+};
+
+void
+print_error(struct msph_ctx *ctx)
+{
+	size_t i;
+	const char *err_msg;
+
+	err_msg = NULL;
+	for (i = 0; errinfo[i].err != -1; i++) {
+		if (ctx->err == errinfo[i].err) {
+			err_msg = errinfo[i].msg;
+			break;
+		}
+	}
+	if (err_msg == NULL) {
+		err_msg = "unknown error";
+	}
+
+	fprintf(stderr, "ERROR(%x, %d):%s\n", ctx->err, ctx->err_info, err_msg);
+
+	if (ctx->err == MSPH_ERR_SPHOPHI)
+		fprintf(stderr, "\t%s\n", spho_ctx_strerror(ctx->spho));
+}
+
+struct msph_opts {
+	int		tokenize_only;
+	int		parser;
+	const char	*in_path;
+	const char	*out_path;
+} run_opts = {
+	0,
+	MSPH_PARSE_INFIX,
+	NULL,
+	NULL
+};
+
 int run(struct msph_opts *);
 
 int
@@ -98,6 +144,7 @@ run(struct msph_opts *opts)
 	struct msph_tree_root *root;
 	FILE *in, *out;
 
+
 	in = out = NULL;
 	s = NULL;
 	root = NULL;
@@ -157,13 +204,7 @@ exit:
 	return (0);
 
 err:
-	if (root != NULL && ctx.err == MSPH_ERR_SPHOPHI) {
-		fprintf(stderr, "ERROR:%s\n",
-		    spho_ctx_strerror(ctx.spho));
-	} else {
-		fprintf(stderr, "ERROR:msph_err: %x (%d)\n", (ctx).err,
-		    (ctx).err_info);
-	}
+	print_error(&ctx);
 
 	if (in)
 		fclose(in);
@@ -173,6 +214,7 @@ err:
 }
 
 
+
 void
 msph_ctx_init(struct msph_ctx *ctx)
 {
diff --git a/src/msph/token.c b/src/msph/token.c
index abe2677..81f61c7 100644
--- a/src/msph/token.c
+++ b/src/msph/token.c
@@ -7,7 +7,7 @@
 
 #include "spho/spho.h"
 
-#include "msph/err.h"
+#include "msph/msph.h"
 #include "msph/token.h"
 
 
diff --git a/src/msph/tree.c b/src/msph/tree.c
index 87d99d7..2444da6 100644
--- a/src/msph/tree.c
+++ b/src/msph/tree.c
@@ -1,6 +1,5 @@
 #define SPHO_ENABLE_DEBUG_PRINT
-#include "msph/common.h"
-#include "msph/common.h"
+
 
 #include <sys/queue.h>
 
@@ -10,6 +9,7 @@
 
 #include "spho/spho.h"
 
+#include "msph/msph.h"
 #include "msph/tree.h"
 
 
@@ -130,6 +130,8 @@ msph_tree_makeroot(struct msph_ctx *ctx)
 	return (root);
 }
 
+#define __POS_FMT		"line: %u, col: %u"
+#define __POS_ARGS(pos)		(pos).line, (pos).col
 
 /*
  * Expect to read next token, otherwise set error and do something
@@ -143,6 +145,8 @@ msph_tree_makeroot(struct msph_ctx *ctx)
 		if (((readres) = tree_parse_next_token(parse)) == -1) \
 			on_err; \
 		if ((readres) == 0) { \
+			fprintf(stderr, "unexpected end-of-file after " \
+			    __POS_FMT "\n", __POS_ARGS((parse)->s->src.pos)); \
 			MSPH_ERR_INFO(CTX(parse), MSPH_ERR_TREE_EOF, \
 			    err_info); \
 			on_err; \
@@ -159,6 +163,8 @@ msph_tree_makeroot(struct msph_ctx *ctx)
 #define EXPECT_CURR_TOKEN(parse, toktype, err_info, on_err) \
 	do { \
 		if (CURR_TOKEN(parse)->type != toktype) { \
+			fprintf(stderr, "parser expected token " #toktype \
+			    "\n"); \
 			MSPH_ERR_INFO(CTX(parse), MSPH_ERR_TREE_NOMATCH, \
 			    err_info); \
 			on_err; \
@@ -1062,7 +1068,6 @@ err:
 struct msph_tree_tpexpr *
 tree_parse_tpname_or_tpappl(struct tree_parse *p, struct msph_tree *parent)
 {
-	int res;
 	struct msph_tree_tpname *tpname;
 	struct msph_tree_tpexpr *ret;
 	struct msph_tree_nameref *nameref;
@@ -1074,7 +1079,6 @@ tree_parse_tpname_or_tpappl(struct tree_parse *p, struct msph_tree *parent)
 		return (NULL);
 
 	if (CURR_TOKEN(p)->type == TOK_LBRAK) {
-		EXPECT_READ_NEXT(res, p, MSPH_TREE_TPAPPL, goto err);
 		if ((ret = tree_parse_tpapplargs(p, nameref, parent)) == NULL) 
 			goto err;
 		return (ret);