diff --git a/src/lisp/istream.c b/src/lisp/istream.c
new file mode 100644
index 0000000..9351adf
--- /dev/null
+++ b/src/lisp/istream.c
@@ -0,0 +1,208 @@
+#include "istream.h"
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct stristream_private
+{
+	char *val;
+	int i;
+	int length;
+	int line;
+	int fromleft;
+	int linestart;
+};
+
+int stristream_peek(struct istream *is)
+{
+	struct stristream_private *p = is->data;
+
+	if (p->i < p->length)
+		return p->val[p->i];
+	else
+		return -1;
+}
+
+int stristream_get(struct istream *is)
+{
+	struct stristream_private *p = is->data;
+
+	if (p->i < p->length)
+	{
+		char c = p->val[p->i++];
+
+		p->fromleft++;
+
+		if (c == '\n')
+		{
+			p->fromleft = 1;
+			p->line++;
+			p->linestart = p->i;
+		}
+
+		return c;
+	}
+	else
+		return -1;
+}
+
+int stristream_read(struct istream *s, char *buffer, int size)
+{
+	struct stristream_private *p = s->data;
+
+	int len = MIN(size, p->length - p->i);
+	memcpy(buffer, p->val, len);
+	return len;
+}
+
+void stristream_showpos(struct istream *s, FILE *out)
+{
+	struct stristream_private *p = s->data;
+
+	fprintf(out, "line: %d, char %d\n", p->line, p->fromleft);
+
+	int end = p->length;
+
+	for (int i = p->linestart; i < p->length; i++)
+	{
+		if (p->val[i] == '\n')
+		{
+			end = i;
+			break;
+		}
+	}
+
+	fprintf(out, "  | %.*s\n", end - p->linestart, p->val + p->linestart);
+	fprintf(out, "  | ");
+	for (int i = 0; i < p->fromleft - 1; i++)
+		fprintf(out, " ");
+
+	fprintf(out, "\033[31m^\033[0m\n");
+}
+
+struct istream *new_stristream(char *str, int length)
+{
+	struct istream *is = malloc(sizeof(struct istream));
+	struct stristream_private *p = malloc(sizeof(struct stristream_private));
+
+	p->val = strndup(str, length);
+	p->i = 0;
+	p->length = length;
+	p->line = 1;
+	p->fromleft = 1;
+	p->linestart = 0;
+
+	is->data = p;
+	is->get = stristream_get;
+	is->peek = stristream_peek;
+	is->read = stristream_read;
+	is->showpos = stristream_showpos;
+
+	return is;
+}
+
+void del_stristream(struct istream *stristream)
+{
+	struct stristream_private *p = stristream->data;
+	free(p->val);
+	free(p);
+	free(stristream);
+}
+
+struct istream *new_stristream_nt(char *str)
+{
+	return new_stristream(str, strlen(str));
+}
+
+struct fistream_private
+{
+	FILE *file;
+	int next;
+	bool has_next;
+};
+
+int fistream_peek(struct istream *is)
+{
+	struct fistream_private *p = is->data;
+
+	if (p->has_next)
+		return p->next;
+
+	p->next = fgetc(p->file);
+	p->has_next = true;
+	return p->next;
+}
+
+int fistream_get(struct istream *is)
+{
+	struct fistream_private *p = is->data;
+
+	if (p->has_next)
+	{
+		p->has_next = false;
+		return p->next;
+	}
+
+	return fgetc(p->file);
+}
+
+int fistream_read(struct istream *is, char *buffer, int size)
+{
+	struct fistream_private *p = is->data;
+
+	int offset = 0;
+
+	if (p->has_next)
+	{
+		*buffer = p->next;
+		p->has_next = false;
+		buffer++;
+		size--;
+		offset = 1;
+	}
+
+	return (int)fread(buffer, 1, size, p->file) + offset;
+}
+
+void fistream_showpos(struct istream *s, FILE *out)
+{
+	// TODO: implement
+}
+
+struct istream *new_fistream(char *path, bool binary)
+{
+	struct istream *is = malloc(sizeof(struct istream));
+
+	FILE *fp = fopen(path, binary ? "rb" : "r");
+
+	if (fp == NULL)
+	{
+		free(is);
+		return NULL;
+	}
+
+	struct fistream_private *p = is->data =
+	    malloc(sizeof(struct fistream_private));
+
+	p->has_next = false;
+	p->file = fp;
+
+	is->data = p;
+	is->get = fistream_get;
+	is->peek = fistream_peek;
+	is->read = fistream_read;
+	is->showpos = fistream_showpos;
+
+	return is;
+}
+
+void del_fistream(struct istream *is)
+{
+	struct fistream_private *p = is->data;
+
+	fclose(p->file);
+
+	free(is->data);
+	free(is);
+}